SPH4U LAB MANUAL
Table of Contents
LABS
1.
3.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Lab Write-Ups
Graphing Rules
Using the Equipment
2
4
6
Period of a Pendulum
Data Analysis with LED’s
Acceleration of a Cart Down a Ramp
Projectile Motion
Principle of Equivalence
Conservation of Energy in a Cart on a Ramp
Conservation of Momentum
Millikan Oil Drop Experiment
Strength of a Magnetic Field in a Helix
Wavelength of a Laser
Thickness of a Human Hair
Finding Planck’s Constant Using the Photoelectric Effect
10
11
13
13
15
16
18
19
20
21
22
23
Scientific Investigation Skills
The following lab activities are designed to satisfy many of these SIS expectations.
Overall Expectations
Throughout this course, students will:
A1. demonstrate scientific investigation skills (related to both inquiry and research) in the four areas of skills (initiating and
planning, performing and recording, analysing and interpreting, and communicating);
A2. identify and describe careers related to the fields of science under study, and describe the contributions of scientists, including
Canadians, to those fields.
A1. Scientific Investigation Skills
Specific Expectations
Throughout this course, students will:
Initiating and Planning [IP]
A1.1 formulate relevant scientific questions about observed relationships, ideas, problems, or issues, make informed predictions,
and/or formulate educated hypotheses to focus inquiries or research
A1.2 select appropriate instruments (e.g., pendulums, springs, ripple tanks, lasers) and materials (e.g., sliding blocks, inclined
planes), and identify appropriate methods, techniques, and procedures, for each inquiry
A1.3 identify and locate a variety of print and electronic sources that enable them to address research topics fully and
appropriately
A1.4 apply knowledge and understanding of safe laboratory practices and procedures when planning investigations by correctly
interpreting Workplace Hazardous Materials Information System (WHMIS) ymbols; by using appropriate techniques for handling
and storing laboratory equipment and materials and disposing of laboratory materials; and by using appropriate personal
protection
Performing and Recording [PR]
A1.5 conduct inquiries, controlling relevant variables, adapting or extending procedures as required, and using appropriate
materials and equipment safely, accurately, and effectively, to collect observations and data
A1.6 compile accurate data from laboratory and other sources, and organize and record the data, using appropriate formats,
including tables, flow charts, graphs, and/or diagrams
A1.7 select, organize, and record relevant information on research topics from a variety of appropriate sources, including
electronic, print, and/or human sources, using suitable formats and an accepted form of academic documentation
Analysing and Interpreting [AI]
A1.8 synthesize, analyse, interpret, and evaluate qualitative and/or quantitative data; solve problems involving quantitative data;
determine whether the evidence supports or refutes the initial prediction or hypothesis and whether it is consistent with scientific
theory; identify sources of bias and/or error; and suggest improvements to the inquiry to reduce the likelihood of error
A1.9 analyse the information gathered from research sources for logic, accuracy, reliability, adequacy, and bias
A1.10 draw conclusions based on inquiry results and research findings, and justify their conclusions with reference to scientific
knowledge
Communicating [C]
A1.11 communicate ideas, plans, procedures, results, and conclusions orally, in writing, and/or in electronic presentations, using
appropriate language and a variety of formats (e.g., data tables, laboratory reports, presentations, debates, simulations, models)
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A1.12 use appropriate numeric (e.g., SI and imperial units), symbolic, and graphic modes of representation (e.g., vector diagrams,
freebody diagrams, vector components, and algebraic equations)
A1.13 express the results of any calculations involving data accurately and precisely, to the appropriate number of decimal places
or significant figures
MIDDLEFIELD C.I – SCIENCE DEPARTMENT
LAB REPORT FORMAT (GRADE 12)
Laboratory activities in science are an excellent learning device. Besides providing enjoyable opportunities for group
dynamics, and skill development, they also amplify the theory by concrete example. Often, lab activities can illustrate
exceptions, enhance problem solving, provide the opportunity for in-depth or lateral thinking or allow for the
development of critical analysis and error analysis.
However, the lab report remains an important form of evaluation of the lab activity. In the junior sciences you were
exposed to a fixed report format. This format was structured to allow you to report your findings in a universal
manner. You were challenged to hypothesize, evaluate your results and present your findings in the most appropriate
manner possible. In Grade 12, you will be expected to continue and refine this process. As such, evaluation of these
reports will include both content and your abilities to express yourself in the report form.
Expectations will include your ability to:
follow the required format
record, present and manipulate data in the most appropriate manner
evaluate your results with respect to experimental errors
comprehend the theoretical principles and apply them to “Discussion” questions
use proper sentence structure, grammar and spelling
The following describes the format to be followed when writing up lab report for Grade 12. At the senior level labs
are varied. Although it is possible that all aspects of this format may not apply in every case, you are to use this
format for all lab reports leaving out only those parts, which have been specifically deleted by your teacher.
GENERAL
1. Avoid the use of personal pronouns. Use the third person passive tense.
2. Indent all text away from key headings (as you see below).
3. Include a meaningful title and ensure that the title, student’s name, teacher’s name, date and course code appear at
the top of the first page or on a separate title page.
TITLE
By Grade 12 you do not need a separate "purpose". The title of the lab should be written to
reflect the reason for the lab.
ABSTRACT
This is a brief synopsis of the lab and the results. Although it appears after the title it must
be written after the rest of the lab has been completed in order to reflect the entire lab and
results obtained.
THEORY
You may be expected to research the theoretical aspects of the lab or present a brief
synopsis of the lab results or expectations. You should express what you intend to
determine and how you expect to determine it.
APPARATUS &
METHOD
This section lists the materials you will use and how you will set up the equipment.
Your information may be set-up as one of the following (as indicated by your teacher):
a labelled/annotated diagram (always required in Physics)
reference to a source with exceptions if necessary
numbered steps
a flow chart with diagrams
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OBSERVATIONS
In this section, you will present your findings. Depending on the lab, they may be visual
descriptions, numerical data or a chart or table of values. You must choose the best possible
method of presentation for the data you collect. This requires an understanding of the lab
procedure and purpose, and to know before hand what you will be looking for and what you
might be expected to do with the data.
CALCULATIONS
&
MANIPULATIONS
Depending on the lab, you may need to perform calculations, manipulate your
data, draw tables, charts, or graphs. You will be expected to make proper use of
significant figures. Calculations must show all relevant steps. Multiple and repetitive
calculations need only show one full example. Graphs should be large and properly
labelled. You are responsible for choosing the best method of presentation of your
calculated results.
DISCUSSION
QUESTIONS
In this section, you will answer all questions on the lab sheet or in the text
that are directly related to the lab. Answers should be presented as fully calculated
problems, or full sentences for explanations.
EXPERIMENTAL
UNCERTAINTIES
Experimental errors are those that arise because of experimental design or
equipment. They do NOT include human errors - errors in reading or measuring. Your
errors must be appropriate to your result i.e. an error which accounts for a high result cannot
be used to explain your LOW one. Error analysis should be in numbered sentences in
decreasing order of effect. IN PHYSICS, AT LEAST THREE EXPERIMENTAL
UNCERTAINTIES ARE REQUIRED. THE INSTRUMENTAL UNCERTAINTIES OF
ALL THE EQUIPMENT USED TOGETHER COMPRISE ONE OF YOUR
UNCERTAINTIES.
CONCLUSION
The “conclusion” is a brief expression about the outcome of your lab. The conclusion
should address the purpose of the lab.
EXTENSION
QUESTIONS
Answer all extension questions from the lab sheet or text. Answers should be
complete, as expected in the “Discussion” section. For self designed methods, include real
life applications and interesting facts to your process.
Labs may be hand written as long as they are legible.
USEFUL HINTS FOR LABS
1. Learn the difference between “trial” and “trail”. Use a spell checker AND proof-read.
2. Entering Greek letters: Type the corresponding English letter and switch that letter to the
“symbol font” (on your fonts menu).
A B
C D
E
F
G H
I
J
Α Β Χ ∆
Ε
Φ Γ
a
b
c
d
e
f
α
β
χ
δ
ε
φ
K
L M N O
P
Q R
S
T
U V W X Y
Η
Ι
ϑ Κ Λ Μ Ν Ο Π Θ
g
h
i
j
k
l
m
n
o
p
γ
η
ι
ϕ
κ
λ
µ
ν
ο
π
Ρ
Σ
Τ
Υ
ς
Ω Ξ Ψ Ζ
q
r
s
t
u
v
w
x
y
z
θ
ρ
σ
τ
υ
ϖ ω
ξ
ψ
ζ
Another way to get Greek letters is to use the “Insert” menu and click on “Symbol”.
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Z
3.
Comparing values:
Values may be compared using using the % error formula:
% error = ((measured – predicted) / predicted) x 100%
OR the %difference formula:
%diff = (|measure 1 – measure 2| / average of 2 measures) x 100%
4.
Superscripts & Subscripts:
To superscript something hold down ctrl-shift and hit “+”.
To subscript something hold down ctrl and hit “=”.
The above keystrokes turn the function on and off.
5.
Experimental Uncertainties:
Instrumental Uncertainties – one of your uncertainties is always instrumental. You
should describe for each instrument the limitation in its precision. For example, a
metre stick marked in mm markings can only measure to the nearest mm (or .5 mm
if you are careful). THIS IS NOT A MANUFACTURING ERROR NOR DOES
IT MEAN THAT THE INSTRUMENT IS BROKEN OR NOT WORKING.
Procedural Uncertainties – describe what aspects of your procedure lead to
imprecise or inaccurate data. MAKING A MISTAKE IS NOT AN
UNCERTAINTY. IF YOU MAKE A MISTAKE, YOU REDO THE
MEASUREMENT.
Do not include uncertainties that never occurred.
Address the anomalies in your lab!
6.
Use proper English. If your grammar, sentence structure or spelling interferes with
the clarity of what you are trying to say, you will lose format marks. USE THE
CORRECT WORD TO DESCRIBE YOUR SITUATION. WORDS LIKE
“LEVEL, HORIZONTAL, PARALLEL, STRAIGHT” HAVE SPECIFIC
MEANINGS AND SHOULD NOT BE CONFUSED.
GRAPHING RULES
GRAPHS ARE MEASURING INSTRUMENTS – THEY NEED TO BE MADE AS PRECISE AS
POSSIBLE. THIS IS THE GUIDING PRINCIPLE FOR EVERYTHING THAT FOLLOWS BELOW.
All Graphs
1.
All graphs need fully labelled axes including the variable being plotted and the unit used.
2.
Graphs should have a meaningful title. A title that just repeats the axis labels is not sufficient.
3.
The graph axes should be chosen so that the data points are widely spread across the entire graph in
both the horizontal and vertical directions.
Hand-Drawn Graphs
1.
2.
3.
4.
5.
Hand drawn graphs must be done on graph paper. Graphs not done on graph paper are automatically
worth 0 marks.
Graphs must be done in pencil.
The entire sheet of graph paper should be used so that the data spreads out over most of the sheet.
The data points must be plotted clearly and visibly (make them dark enough).
Best fit straight lines are drawn with a ruler so that the line comes as close as possible to every data
point. The points not on the line should be roughly evenly spread on either side of the line. In the
case where the data is obviously curved and intended to be curved, draw the best fitting curve
freehand.
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6.
Slope and intercept calculations may be done right on the graph. The rest of the analysis should be
done in the appropriate section of the lab report.
Computer Generated Graphs
1.
2.
3.
4.
Computer generated graphs may be analyzed by hand or by computer. If the data points are plotted
by computer, but the best fit line is drawn by hand or if the slope of the best fit line is calculated by
hand, then the graph must follow rules 3-6 for hand-drawn graphs.
If the computer is used to plot the best fit line, and also used to determine the equation of the best fit
line, then the graph may be smaller than a whole page. Once the equation is found, do not forget to
extract the parts of the result you want and state YOUR ANSWER. Often the equation of the best fit
line is not quite your final result.
Do not include the line joining the data points. If your program draws this by default, then you must
turn it off.
Computer generated graphs should be cut and pasted into the proper spot in your lab report.
The simplest way to do a computer generated graph is to use a spreadsheet like Microsoft Excel. The
following instructions apply to Microsoft Excel 2003. Other versions or other spreadsheets will do
something similar.
1.
2.
3.
4.
5.
Enter your data for the independent variable (X-axis) into column A.
Enter the dependent data (Y-axis) in column B.
Select your data (click and drag the mouse over it until it is all highlighted).
Click on the Chart icon at the top of the screen.
Select X-Y scatter plot as the chart type and as the subtype, select the one that plots only the dots with no
lines.
6. Click next to see a preview of your graph. Click next again and enter a graph title and axis labels.
7. Click next and then finish. You now have a graph on your spread sheet.
8. Place your cursor directly on one of your data points and right-click. Select “Add trend line”.
9. On the trendline menu, select Linear if you are fitting a straight line Polynomial of Order 2 to fit a
quadratic. Click on the Options tab and select the option “Display Equation on the Graph”. Click OK.
10. Finally, on your graph,, if you do not need the legend, right click on it and select Clear.
You can now cut and paste this graph into your lab report.
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USING THE EQUIPMENT
The Stopwatch
The typical class stopwatch has a smallest increment of 0.01 s. However, its major source of error is in the
judging of when to start and stop it. The error can be minimized when measuring a periodic motion by
measuring the single time interval over multiple periods and dividing the time by the number of periods.
When the motion is not periodic, but can be repeated, multiple trials under the same conditions can be
averaged to produce a better time.
The Metre Stick
The typical class metre stick has smallest increments of 1 mm or 0.1 cm. Typical other sources of error
usually involve trying to ensure the metre stick is not tilted in any way with respect to the length being
measured. It needs to be parallel to the particular dimension in question.
The Spring Scale
Each spring scale has a different smallest increment. It is up to the student to study the scale and determine
its value. The student should also always confirm the calibration. Hold the scale vertical with nothing
hanging from it and adjust the plastic nut until the scale reads zero newtons. Internal friction inside the scale
tube will affect the readings.
The Ticker Tape Timer
Also called a period timer or an electric bell clapper, this device produces both time and distance data
simultaneously. The smallest increment of time is 1/60 s or 0.017 s.
Position—Time Data
In general, the first clearly distinguishable dot can be marked as the start point. The space until the next
point is 1/60 s. Six of these spaces is therefore 0.10 s (2 sig figs). Divide the dots into groups of 6 spaces.
Measure the distance from the beginning dot to the start of each 6 space interval to get the positions. Create
a data table. A plot of this data will reveal various velocities through the analysis of the slope.
Velocity-Time Data
Once position-time data is recorded, it can be analyzed to produce velocity-time data. The average velocity
can be calculated over each 6 space interval using ∆d/∆t. To plot a velocity-time graph, one can assume that
the average velocity over the interval is equal to the instantaneous velocity at the mid-point of the interval.
For example, if the average velocity from 0.10 s to 0.20 s is 3.4 cm/s, then the instantaneous velocity at 0.15
s is also 3.4 cm/s. In this fashion, a table of velocity-time data may be produced and plotted in a velocitytime graph. Analysis of slopes in this graph will produce accelerations and areas between the velocity curve
and the time axis will produce displacement data.
The Calculator-Based Laboratory (CBL)
The CBL is essentially a voltmeter with a timing function. For the purpose of this course, we will assume
the CBL measures time intervals acccurate to 0.001 s (ten times better than a stopwatch). We have two
different type of CBL in class. The grey and yellow ones are the original CBL’s. We will call them CBL-1.
The black ones are called CBL-2. Though they both do the same things, they do them differently.
Various probes can be attached to the CBL’s. Mostly we will use photogates, and motion sensors.
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A
photogate is a black U-shaped piece of plastic. An invisible infrared beam crosses over the open end of the
U and the CBL can measure times as objects break the beam. Four of our photogates are digital. All the
photogates connect via a connector that looks like a phone cord connector. The digital gates also have a
second connection that looks like the ones on the CBL. The digital photogates must go with the CBL-2’s
and the analog photogates go with the CBL-1’s.
The motion sensor is a blue device with sound generator that folds up. It sends out high pitched clicks and
listens for the return echo to determine times. There is a similar grey device, but it won’t work following the
instructions below.
The CBL is controlled through a connected graphing calculator (TI-83+ or TI-84+). Both the types of
graphing calculators work exactly the same (at least for our purposes).
CBL-1 With Photogate and Picket Fence
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
16.
17.
Connect an analog photogate (only has the “phone connector) to channel 1 of the CBL-1 and connect
the TI-83+ to the CBL.
On the TI-83+, press the “Apps” button and select “Physics” off the menu.
On the MAIN MENU, select “Set up Probes”
For NUMBER OF PROBES, select “One”
For SELECT PROBE, select “Photogate”. You may have to select “More” a couple times until
“Photogate” appears.
For TIMING MODES, select “Motion”.
For MOTION TIMING, select “Select Device”.
For SELECT DEVICE, select “Vernier Picket”.
Back at MOTION TIMING, select “Collect Data”. This will activate the photogate.
Drop the picket fence through the photogate or put it on a cart and allow the cart to carry it through
the photogate. Each time one of the black bands passes through the photogate, the calculator records
the time and adds 5.0 cm to the distance.
Check the graph you are interested in. If you are trying to find a constant velocity, you want to look
to see if the distance-time graph is fairly straight. If you are trying to find a constant acceleration,
check to see if the velocity-time graph is fairly straight.
For REPEAT, select “No” if your graph looked fine, else select “Yes” and collect a new set of data.
For TIMING MODES, select “Return To Main”.
For MAIN MENU, select “Analyze”.
For ANALYZE MENU, select “Curve Fit”.
For CURVE FIT, select “Linear L1, L5” for a velocity-time graph. The equation of the velocity-time
data is displayed. Y is the velocity, X is the time. A is the slope (acceleration) and B is the Yintercept (initial velocity). R is the correlation coefficient. If R is close to “1”, the data is very
straight. You should get values typically better than 0.97. Otherwise, you should recollect your data.
For MAIN MENU, select “Collect Data” to collect more data or select QUIT to exit is you are done.
If you wish, your data from your last run is still available in the calculator. Press SHIFT L1 to get
the time data, SHIFT L4 to get the distance data, SHIFT L5 for the velocity data and SHIFT L6 for
the acceleration data.
CBL-2 With Photogate and Picket Fence
1.
2.
3.
Attach a digital photogate to the dig/sonic port on the CBL-2. If your setup does not work, see your
teacher as you may not have a digital photogate. Make sure you are connecting using the “phone”
style connector on the photogate. Also attach the TI-84+ to the CBL-2.
Press PRGM on the calculator and select the program DATAGATE.
Press “1” to enter SETUP. Press “1” to select MOTION. Press “1” to select VERNIER PICKET
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4.
5.
6.
7.
8.
9.
10.
11.
FENCE. Select “1” for OK. A Vernier Picket Fence is a strip of clear plastic with 8 black bands
across it every 5.0 cm.
Press “2” to start collecting data. This will activate the photogate. Drop the picket fence through
the photogate or put it on a cart and allow the cart to carry it through the photogate. Each time one
of the black bands passes through the photogate, the calculator records the time and adds 5.0 cm to
the distance.
Check the graph you are interested in. If you are trying to find a constant velocity, you want to look
to see if the distance-time graph is fairly straight. If you are trying to find a constant acceleration,
check to see if the velocity-time graph is fairly straight.
Press “1” to return to the MAIN MENU.
Press “4” to select ANALYZE. Press “2” to select CURVE FIT.
Select the type of curve to fit. Usually, select “2” to fit a straight line to the velocity-time data. The
equation of the velocity-time data is displayed. Y is the velocity, X is the time. A is the slope
(acceleration) and B is the Y-intercept (initial velocity). R is the correlation coefficient. If R is
close to “1”, the data is very straight. You should get values typically better than 0.97. Otherwise,
you should recollect your data.
Press ENTER until the menu returns. Select “3” to return to the ANALYZE screen. Press “1” to
return to the MAIN MENU.
Press “2” to start collecting your next data set, or if you are done, press “5” to exit.
If you wish, your data from your last run is still available in the calculator. Press SHIFT L1 to get
the time data, SHIFT L2 to get the distance data, SHIFT L3 for the velocity data and SHIFT L4 for
the acceleration data.
CBL-1 with Motion Sensor
1.
2.
3.
4.
5.
6.
7.
Connect the motion sensor to the SONIC port on the CBL-1.
On the TI-83+, press the “Apps” button and select “Physics” off the menu.
On the MAIN MENU, select “Set up Probes”
For NUMBER OF PROBES, select “One”
For SELECT PROBE, select “Motion.
Select “Collect Data” and then from the MAIN MENU, select “Time Graph”.
For TIME BETWEEN SAMPLES, enter 0.05 seconds and for NUMBER OF SAMPLES, enter 100.
For CONTINUE, select “Use Time Setup” unless you made a mistake and wish to change it.
Ensure your cart is ready to go. Press “Enter” on the calculator and release your cart.
When done, for SELECT GRAPH, select “Next” and for REPEAT, select “Yes” to gather data again.
NOTE: data gathered with the motion sensor is sometimes less reliable than using a picket fence. However,
it is direction sensitive unlike a picket fence.
CBL-2 with Motion Sensor
1.
2.
3.
4.
5.
Connect the motion sensor to the DIG/SONIC port on the CBL-2.
Press the APPS button on the TI-84+ calculator and select EASYDATA off the menu. It should
automatically determine that you have a motion sensor attached and immediately start showing
distances with the motion detector clicking about one a second.
To gather distance-time data, Press SETUP. Select TIME GRAPH off the menu. The default time
graph settings are usually fine, but press EDIT if you wish to change them. Press OK when done.
Press START to start collecting data. By default a distance-time graph is plotted. Press PLOTS to
view the graph you want.
Press ANALYZE to do calculations on your graph. Selecting Linear fit will fit a straight line. The
equation is the best fit line is displayed.
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6.
Press MAIN to return to the main menu. Press START to gather another data set or QUIT to exit.
NOTE: data gathered with the motion sensor is sometimes less reliable than using a picket fence. However,
it is direction sensitive unlike a picket fence.
Using the CBL-1 and Photogate to Time Events.
The photogate can be used in GATE mode to measure how long a single object blocks the beam in the gate
or in PENDULUM mode to measure the period of a pendulum bob passing through the gate.
1.
Connect an analog photogate (only has the “phone connector) to channel 1 of the CBL-1 and connect
the TI-83+ to the CBL.
2.
On the TI-83+, press the “Apps” button and select “Physics” off the menu.
3.
On the MAIN MENU, select “Set up Probes”
For NUMBER OF PROBES, select “One”
For SELECT PROBE, select “Photogate”. You may have to select “More” a couple times until
“Photogate” appears.
4.
For TIMING MODES, select either GATE or PENDULUM and carefully follow the instructions on
the screen. In both modes ensure nothing is initially blocking the beam when you activate the
photogate. Once activated, anything passing into the beam starts the timing.
Using the CBL-2 and Photogate to Time Events.
The photogate can be used in GATE mode to measure how long a single object blocks the beam in the gate
or in PENDULUM mode to measure the period of a pendulum bob passing through the gate.
1.
Attach a digital photogate to the dig/sonic port on the CBL-2. If your setup does not work, see your
teacher as you may not have a digital photogate. Make sure you are connecting using the “phone”
style connector on the photogate. Also attach the TI-84+ to the CBL-2.
2.
Press PRGM on the calculator and select the program DATAGATE.
3.
Press “1” to enter SETUP.
4.
For TIMING MODES, select either GATE or PENDULUM and carefully follow the instructions on
the screen. In both modes ensure nothing is initially blocking the beam when you activate the
photogate. Once activated, anything passing into the beam starts the timing.
Page 9 of 24
Data Analysis on the Period of a Pendulum
Purpose:
To determine the relationship between the period and length of a pendulum.
Apparatus:
- retort stand, ring clamp, 100 g mass, string,
Method:
1.
2.
3.
Create a pendulum using the retort stand, string, ring clamp and mass.
Using either a stopwatch, or electronic CBL’s in PENDULUM mode, determine the period of the
pendulum.
Design and conduct an experiment to determine the relationship between the period and the length of a
pendulum.
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Data Analysis with LED’s
Credit for this lab idea goes the Perimeter Institute for Theoretical Physics.
Background:
LED’s or Light Emitting Diodes are becoming more popular in everyday lighting applications. Essentially, they
are diodes. Diodes allow current to flow only in one direction once a minimum voltage is applied. In an LED,
essentially, the applied voltage gives electrons enough energy to overcome a barrier and once they do so, the
electrons release the same energy in the form of light. You will learn more about this later in the course when
you study quantum physics.
Purpose:
To determine the relationship between the minimum voltage needed to operate an LED and the wavelength of
the light emitted.
Expectations:
Grade 12 (SPH4U)
SIS.05
- compile, organize, and interpret data, using appropriate formats and treatments, including tables, flow charts, graphs, and
diagrams (e.g., interpret data, using graphs and graphical analysis techniques; explain, using a ray diagram, the operation of
an optical instrument);
SIS.10
- communicate the procedures and results of investigations and research for specific purposes using data tables, laboratory
reports, and research papers, and account for discrepancies between theoretical and experimental values with reference to
experimental uncertainty;
Procedure:
1.
CAUTION: DO NOT STARE DIRECTLY AT A BRIGHTLY LIT LED.
Turn the knob of the potentiometer fully clockwise. Orient the potentiometer so the connection tabs are towards
you. There are 3 tabs (if your potentiometer has 5 tabs, ignore the outermost ones and use only the middle 3).
Connect the leftmost tab to the negative terminal (DC common) on the power supply. Connect the rightmost tab
to the positive 6V terminal of the power supply. Make sure your power supply is turned off. (If you have one of
the newer Bench Power Supplies, the black DC connector is negative and the red is positive. Set the dial to 6V,
but do not turn the power on yet.) See Figure 1.
Figure 1
6V Power
supply
-
+
LED
330 Ω resistor
2.
3.
4.
CBL
Connect the 330 W resistor to the middle tab of the potentiometer. This is tricky as the tabs are very close
together and THEY CANNOT TOUCH EACH OTHER. Use small alligator clips where possible and make use
of the plastic covers if possible.
Connect the other end of the resistor to the negative connection on the red LED. LED’s must be connected
correctly or they do not work. Our LED’s have two connectors of UNEQUAL length. The negative connector
is shorter than the positive connector. This agrees with the symbol we use for a DC cell – the negative line is
shorter. Connect the positive LED connection to the rightmost connection tab (or to the other lead already there)
on the potentiometer. AGAIN, BE CAREFUL NOT TO TOUCH ANY OF THE OTHER TABS OR YOUR
CIRCUIT WON’T WORK.
Finally, connect the voltmeter so that the negative connection (black) is connected to the negative connector on
the LED and the positive connection (red) goes to the positive connection on the LED. For voltmeters, you will
use the CBL units. Connect the voltage probe to Ch1. Plug in the CBL and turn it on. Press the Mode button –
it should say “sampling” and the voltage being measured is displayed. READ the display carefully as the
Page 11 of 24
5.
6.
7.
8.
9.
voltage unit (either V or mV) is rather small. If you have done everything correctly, your circuit should look
like Figure 1.
Place the rubber tube over the LED to act as a light shield. You need to see the point where the LED first starts
to glow. Look in the end of the tube to observe the LED. Eliminate as much of the room light as possible.
While one person watches the LED, another can turn on the power supply and turn the potentiometer knob
counter-clockwise until the LED glows. Adjust until you achieve the dimmest glow possible. Take your time
here and get the best result possible.
Record the minimum voltage to create a glow and record the wavelength of the LED.
Repeat the experiment with each of the other LED’s (amber, yellow, green blue).
You should end up with a table of voltages and wavelengths. Use your data analysis techniques to find an
equation that describes the relationship between the voltage and wavelength. Use the voltage as your dependent
variable – it goes on the vertical axis and your equation will be of the form V = some function of λ.
Page 12 of 24
Acceleration of a Cart Down a Ramp
Purpose:
To analyze the motion of a cart down a ramp.
Using electronic probeware, design and conduct an experiment to determine the acceleration of a cart down a
ramp. Compare you result with the theoretical prediction.
Projectile Motion Lab
Purpose: To determine what launch angle gives the greatest distance when a projectile is launched over a cliff.
Theory: When a projectile is launched over a level plane, the horizontal range is given by
v12
sin 2θ
g
where v1 is the initial speed
∆x =
and θ is the launch angle
Analysis of the above equation shows that the greatest ∆x value is obtained at a launch angle of 450. To determine if
this is still true when the vertical displacement is not zero, different angles will be tried over a cliff edge.
Method:
1.
2.
3.
4.
5.
6.
7.
8.
Start the PROJECTL program. Press <PRGM> and select PROJECTL off the menu. Your screen will display
“prgmPROJECTL”. Press <ENTER>.
At the welcome screen that appears, press <ENTER> again.
Select “Set cliff hght” from the main menu. Enter a value of -100 m for the cliff height. The negative means the
net displacement in the Y direction will be downwards.
Select “Set cliff dist” from the main menu. Enter a value of 0 (zero). This will place the launcher right at the
edge of the cliff.
Select “Set init vel” from the main menu. For speed, enter 30 m/s and for angle start by entering 0.
Select “Fix Window” from the main window and set the following values:
Xmin = -20
Xmax = 180
Ymin = -120
Ymax = 50
Select “Run Simulation” from the main menu. The path is plotted on the screen. When the plot is complete you
can use the left and right arrow keys to move the cursor along the curve and read the values. To find the
horizontal distance travelled, press <ENTER> and read it off the next screen.
Using this program, conduct an experiment to determine the launch angle that produces the greatest horizontal
displacement when fired over the edge of the cliff.
Page 13 of 24
Plotting the Graphs
Plotting the graphs can usually be done in MS Excel. However, we require a special graphing program to analyze sine
relationships. For this we will use Vernier’s Graph Analysis.
1.
Start the program.
2.
Enter the angle data in the X column and the range data in the Y column.
3.
Double click on the “X” at the top of the angle column. Enter “Launch Angle” for the name and “degrees” for
the unit. Enter θ for the short name. You can find Greek letters by clicking on the down arrow to the right of
the box. Click “Done”. Double click on the “Y” above the range data column. Enter “Range” for the name, X
for the short name and “m” for the unit.
4.
Double click in the graph area.
5.
On the window that appears, Enter a title for the graph. Check off the “Interpolate” box and uncheck the
“Connect points” box. Click Done.
6.
Position your cursor over the Y-axis and double click. Under scaling, choose “manual” and set the range from 0
to a number larger than your maximum value. Click “done”. Repeat this for the X-axis.
7.
Click on the “Analyze” menu. Select “Curve Fit”. The data you have should fit some kind of sine curve so
choose the fit Asin(Bx+C)+D. You are going to have to do a manual fit. To the right, you will see boxes where
you can enter the values of A, B, C and D. First enter 0 for D. There is no vertical shift for your curve. For A,
search your range data for the maximum values. The value of A is likely to be a couple metres larger than your
maximum value. Enter such a value for A. In the theory above, it looks like B should be 2. But, the sine
function needs to have angles in radians. This means B should be more like 2*π/180 = 0.035. Start with this
value. Finally start with C = 1. Your results will likely not match this value. Now adjust the values of B and
C until the curve fits as well as you can get to the data. Note that smaller B values stretch the curve horizontally.
Reducing C shifts the curve right (just like you learned in math class). When you are satisfied with the fit, click
OK.
8.
You should now be able to use your cursor to locate the highest point on the curve. There is a display at the
bottom left corner of your graph that has the coordinates of your cursor. Move the cursor to the highest point on
the curve and record the angle at which it occurs. While the cursor is at that point, type “CTRL-C” to copy the
graph. Paste it into your word document. A typical result is seen below.
Page 14 of 24
Principle of Equivalence
Purpose:
To verify the principle of equivalence using Newton's Second Law of Motion.
Apparatus:
- CBL
- TI-83+ graphing calculator
- photogate
- Pasco picket fence
-dynamics track with pulley
- dynamics cart
- set of masses
- string
Method:
1.
Set-up track, cart, photogate and picket fence as shown below:
2.
3.
4.
5.
Ensure the top row of pickets will pass through the photogate.
Everything that moves in the system above will comprise the mass you will measure.
Determine the gravitational mass of the moving components.
Conduct an experiment where you vary the force and measure the acceleration. The slope of the force
vs. acceleration graph will give you the inertial mass. Work out the theory ahead of time.
Page 15 of 24
Conservation of Energy of a Cart on a Ramp
Purpose:
To determine if energy is conserved in a cart projected up a ramp using a spring plunger.
Suggested Apparatus:
- CBL
- TI-83+ graphing calculator
- motion sensor
-dynamics track with pulley
- dynamics cart with spring plunger
- set of masses
- string
Method:
1.
2.
3.
4.
1.
Part 1 – Finding the spring constant.
Set-up track and cart as shown below:
Hang various masses on the string and measure the amount of compression in the spring plunger for each mass.
Plot a Force-Compression graph to determine the spring constant of the plunger.
Determine the energy stored in the spring at maximum compression (you will have to measure maximum
compression x ).
Part 2 – Measuring Gravitational Potential Energies
Remove the pulley and masses and incline the track. Measure the angle of the track to the horizontal.
motion sensor
CBL
TI-83+
retort stand
2.
3.
4.
Fully depress the spring plunger and Place the cart at the bottom of the track so that it is ready to be projected up
the track when the plunger is released.
Place the motion sensor at the top of the track pointed at the cart. Collect distance-time data using MOTION
mode.
When the calculator is finished collecting data, for SELECT GRAPH, select “Distance”. You should get a
graph that looks like the following
Page 16 of 24
5.
6.
If your graph does not look like the above, check where the motion sensor is pointing, select “Next” and for
REPEAT, select “Yes”.
Once you have an acceptable graph, determine the maximum displacement of the cart up the ramp by using your
cursor keys to determine the maximum and minimum distances of the cart from the motion sensor (the
maximum at the top of the first dip and the minimum at the bottom of the first dip).
Conduct different trials varying the track angle or the cart mass each time. For each trial, determine to what
extent energy is conserved.
Minimum write-up components:
Abstract, Theory, Observations, Calculations, Experimental Uncertainties
Page 17 of 24
Conservation of Momentum in an Explosion
Purpose:
To determine if momentum is conserved between two carts exploded apart by a spring plunger.
Apparatus:
- dynamics track
- 2 carts - one with a spring plunger and one without
- 3 x 500 g masses
Method:
1.
2.
3.
4.
5.
Use the leveling foot to ensure the track is level.
Compress the spring plunger on one cart and place the two carts together at rest on the track with the plunger
between them. Release the plunger, and allow the carts to move apart until they hit the ends of the track.
Repeat this process until you locate the spot on the track so that when the carts are released, they hit the ends of
the track at the same time. Record the distance traveled by each cart and the mass of each cart.
Each cart is 500 g mass. Add 500 g to one cart to double its mass. Repeat steps 1 and 2.
Keep repeating steps 1 and 2 until you have completed the mass ratios 1:1, 2:1, 3:1, 3:2.
Compare the mass ratios to the distance ratios (since the carts have the same travel times, time cancels out of the
conservation of momentum equation leaving mass-distance products).
Minimum write-up components:
Abstract, Theory, Observations, Calculations, Experimental Uncertainties
Page 18 of 24
Millikan Oil Drop Simulation
Purpose:
To determine if there is a smallest charge and if so, to determine its value.
Apparatus:
- TI-83+ graphing calculator
Method:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
On the TI-83+ graphing calculator, press the “PRGM” button.
From the PRGM menu, select “Millikan”.
For EXPERIMENT TYPE, select “New Experiment”, unless you have stored data from earlier and you just
wish to add to it – in that case, select “Continue Old”.
From MAIN MENU, select “New Droplet”. You will see a screen like the following:
Use the cursor keys to adjust the voltage until the droplet is suspended. The UP and DOWN arrows on the
keypad decrease and increase the voltage by the current step size (default 100V). The LEFT and RIGHT
decrease and increase the step size in multiples of 10. You must get to the nearest 1 volt to suspend the droplet.
Once you have suspended a droplet, select “Store Data” from the MAIN MENU. Generate new droplets until
you have suspended and stored 40 droplets.
You can view monitor the results of the experiment by choosing “Plot Charges” to see the development of the
step function, or “View Data” to review the data on Plate Separation, Droplet Radius, Voltage and Charge.
There is a practice mode for people who have difficulty suspending the droplet before it is lost. Select “settings”
off the MAIN MENU and select “Freeze Droplet” from the OPTIONS menu. The droplet now will not move
while you adjust the voltage.
Once data has been gathered for 40 droplets, record your voltage, droplet radius, plate separation and charge
data into a table with the data sorted from smallest to largest charge and plot a bar graph or scatter plot of the
charges. This should clearly show a step function which you can analyse to determine the value of the smallest
charge.
In your lab write-up, show a sample calculation for determining the mass of the droplet and the charge on the
droplet.
Minimum write-up components:
Abstract, Theory, Observations, Calculations/Analysis
Page 19 of 24
Strength of a Magnetic Field
Purpose:
To compare a predicted magnetic field strength inside a helix to a measured magnetic field strength.
Apparatus
- Two power supplies
- large (6 cm) air core solenoid (helix)
- current balance
- 2 cm length pieces of light string
- leads
- ammeter that can handle up currents up to 20 A DC
Method:
WARNING – THE POWER SUPPLIES WILL PRODUCE LARGE CURRENTS THAT WILL HEAT UP YOUR
EQUIPMENT AND POSSIBLY DAMAGE IT IF LEFT ON TOO LONG. NEVER LEAVE ANY POWER SUPPLY
TURNED ON ANY LONGER THAN NEEDED TO GET A CURRENT MEASUREMENT OR TO DETERMINE IF
BALANCE HAS BEEN ACHIEVED.
1.
The equation that describes the field strength is B = µ0IN/L. Measure these quantities and find the field
strength. Use the 6 V connection on the power supply.
2.
Set up a current balance so it deflects downwards inside the helix. Add string on the opposite side of the
balance to return it to the same level as when the current was off. The force of gravity on the outside should
therefore be the same as the magnetic force inside the helix. The filed strength inside the coil can then be found
from F=ILB. Measure these quantities and find the field strength. Compare to the strength found in step 1.
Minimum write-up components:
Theory, Observations, Calculations, Experimental Uncertainties
Page 20 of 24
Wavelength of a Laser
Purpose:
To determine the wavelength of a laser using Young's double slit experiment.
Apparatus:
- laser
- retort stand
- test-tube clamp
- slit pattern screen
- piece of paper
Method:
1.
2.
3.
5.
Clamp the slit screen up-right to the retort stand using the test-tube clamp.
Locate the double slit patterns down one side of the slit screen. Shine the laser through the second smallest
double slit pattern. The value of the slit separation for this pattern is d = 0.175 mm.
Measure the appropriate quantities used in our analysis of Young’s double slit experiment to find the
wavelength of the laser.
Compare your result to the accepted value of λ = 6.328 x 10-7 m.
Minimum write-up components:
Theory, Observations, Calculations, Experimental Uncertainties.
Page 21 of 24
Thickness of a Human Hair
Purpose:
To determine the thickness of a human hair using an air wedge.
Expectations:
WA2.02 – identify the interference pattern produced by the diffraction of light through narrow slits (single and double
slits) and diffraction gratings, and analyse it in qualitative and quantitative terms;
WA2.03 – collect and interpret experimental data in support of a scientific theory (e.g., conduct an experiment to observe
the interference pattern produced by a light source shining through a double slit and explain how the data
supports the wave theory of light);
WA2.04 – analyse and interpret experimental evidence indicating that light has some characteristics and properties that
are similar to those of mechanical waves and sound.
Apparatus:
- laser
- retort stand
- test-tube clamp
- meter stick with optical bench feet
- two optical bench lens clamps with diverging lens in each
- two flat blank glass slides
- elastic band
- piece of paper
Method:
1.
2.
3.
4.
5.
Create an air wedge with the two glass slides and a human hair separating the slides at one end. Use an elastic
band to hold the wedge together. Clamp the wedge to the retort stand using the test-tube clamp.
Set up the optical bench with the two diverging lenses placed about 50 cm apart. Place the laser at one end of
the bench so it shines through both diverging lenses.
Place the air wedge so it is at the opposite end of the optical bench and so that the laser beam is shining on the
wedge. The beam diameter should be roughly the width of the glass slides at this point.
Angle the wedge so it is roughly 300 to the beam and place your paper screen to show the beam reflecting from
the air wedge.
Measure the necessary quantities to determine the thickness of the hair. Note that the measurements on the
screen will be too large as the beam is larger than it appears on the actual wedge. Make the appropriate
measurements to determine how to shrink your values to the appropriate size.
Minimum write-up components:
Apparatus and Method, Theory, Observations, Calculations, Experimental Uncertainties.
Page 22 of 24
Measuring Planck’s Constant Using the Photoelectric Effect
Purpose:
To use the photoelectric effect to find Planck’s constant.
Expectations:
ME2.01 – collect and interpret experimental data in support of a scientific theory (e.g., conduct an experiment, or view
prepared slides, to analyse how the emission spectrum of hydrogen supports Bohr’s predicted transition states in
his model of the atom);
ME2.02 – conduct thought experiments as a way of developing an abstract understanding of the physical world (e.g.,
outline the sequence of thoughts used to predict effects arising from time dilation, length contraction, and
increase of mass when an object travels at several different velocities, including those that approach the speed of
light);
Theory:
The photoelectric effect was first explained by Albert Einstein in 1905. When a light of high enough frequency
is shone on a metal, electrons are ejected from the metal. According to Einstein’s explanation, when a photon
hits the metal, the electrons will be ejected from the metal with a range of kinetic energies from 0 J up to some
maximum kinetic energy given by
Ek max = hf − W
where
Ek max is the maximum kinetic energy in J
h = 6.63 x 10-34 Js (Planck’s constant)
f = photon frequency in Hz
W= work function of the metal in J.
The work function (W) of a metal is the minimum energy needed for an electron to be freed from the surface of
the metal. The actual energy needed to free any given electron may be more than the work function; hence, the
range of possible kinetic energies for ejected electrons. Typical work functions for metals are on the order of a
few electron-volts (eV).
The work functions for some metallic elements are:
Metal
Work Function (eV)
Metal
Work Function (eV)
Ag
4.26
Mg
3.66
Al
4.28
Na
2.75
Be
4.98
Ni
5.15
Ca
2.87
U
3.63
Cu
4.65
Pt
5.65
Hg
4.49
Zn
4.33
Table 1 (Ref: http://en.wikipedia.org/wiki/Work_function)
Photon energies can be calculated by
E p = hf = hc where
λ
c = 3.00 x 108 m/s is the speed of light in a vacuum and λ is the wavelength of the photon in m.
Frequency can be found for a photon using
f = c . The kinetic energy of an electron can be found by
λ
applying an opposing or retarding voltage to the electron to see how much is needed to stop it moving. The
kinetic energy of the photon can be determined from the potential energy change of the electron in the retarding
voltage ∆V:
EK = ∆Vq where q is the charge on one electron (1.602 x 10-19 C).
Page 23 of 24
Procedure:
DO NOT AT ANY TIME RESET THE RAM ON THE GRAPHING CALCULATOR (USING <2ND><MEM>AS THIS
WILLERASE THE PROGRAM YOU WILL USE.
1.
Start the PHOTEL program. Press <PRGM> and select “PHOTEL” off the menu. The line “prgmPHOTEL”
will appear on the screen. Press <ENTER> again. A title screen will now appear. Press <ENTER> once more.
You are now at the Start Menu. If you want to start a new experiment, select the first option. The second option
“Continue Old” will allows you to continue an experiment you were working on earlier. Any data you had
stored will not be erased.
2.
If you are starting a new experiment, set the work function. Choose ONE metal from Table 1. Select “Setup
Expt” off the main menu and then select “Set Work Func.” off the Setup Menu and enter your work function.
Work functions must be entered in eV. Record the work function you entered. You will not change this value
for the rest of the experiment.
3.
Set the photon wavelength. Select “Set Wavelength” off the Setup Menu. The wavelength must be entered in
nm. Start with a value of 400 nm (a violet photon). Return to the main menu.
4.
Start the simulation. Select “Run Simulation” off the Main Menu. You will see the main simulation screen:
5.
6.
7.
8.
9.
Pressing <DEL> at any time will generate a photon. Pressing <ENTER> at any time will return you to the Main
Menu.
Press <DEL> to generate a photon. If the photon has enough energy to overcome the work function, an electron
will be emitted and travel form the left-hand plate to the right-hand plate. If no electron is emitted, press
<ENTER> to return to the main menu and change your wavelength to a more energetic photon (lower
wavelength = more energy). Try decreasing your wavelength by 100 nm and running the simulation again to
see if an electron is emitted. Once you have electrons being emitted you are ready to start. (NOTE: For
simplicity, all electrons are ejected with the maximum possible kinetic energy. No lower energy electrons are
generated. In reality, photoelectron energies are not all the same – they vary from 0 J to whatever the maximum
value is as determined by the photon and the work function.)
The electrons are travelling between charged plates. If you put enough voltage across the plates, you can cause
the electron to stop before hitting the negative plate. The electron will then return to the positive plate. Set the
voltage to about 2.0 V. This is often referred to as a retarding voltage.
Voltage can be adjusted up and down by using the up and down arrow keys, respectively. The voltage changes
by the value of the voltage increment (Vstep). Vstep can be changed as well. The left arrow key decreases
Vstep by a factor of 10 (to a minimum of 0.1 V) and the right arrow key increases Vstep by a factor of 10 (to a
maximum of 10.0 V).
Press <DEL> to generate a photon and subsequently a photoelectron. Watch to see if the electron hits the
negative (right-hand) plate. Using trial and error, find the minimum voltage needed to cause the electron to
reverse its direction before hitting the negative plate. Find this voltage to the nearest 0.1 V. Record the
photon wavelength and this minimum voltage. You can store it in the calculator by using the “Store data”
option off the Main Menu.
Press <ENTER> to return to the main menu. Change your wavelength by a small amount (up or down by
approx 20 nm). Repeat step 7 to find the minimum voltage for this wavelength. Repeat this step until you have
created a table of wavelengths and voltages with 8-10 entries.
Calculate the frequency corresponding to each wavelength. Calculate the maximum kinetic energy of each
electron by calculating the potential energy change of the electron as it travels between the plates. Plot this
kinetic energy against the frequency of the photon. If you need to review your data, exit the program and you
can find the wavelengths stored in list 1 (press <2nd><1><ENTER>) and the corresponding minimum voltages
in list 2 (press <2nd><2><ENTER>).
Minimum Requirements: Theory, Observations, Calculations
Page 24 of 24