1
FORCES AND TORQUE
PROCEDURE
Trial One
1.
2.
3.
4.
5.
Find the center of gravity of a meter stick ruler by balancing it on a pencil or pen.
Determine the mass of the ruler using a scale.
Support the ruler at the 30 cm mark. You may use a stand or hang the ruler from a ring stand with string.
Hang a 200 gram mass at the 10 cm mark and a 100 gram mass at the 20 cm mark as shown below.
Hang a second 100 gram mass on the opposite side so that the ruler is exactly in balance.
Trial Two
1. Support the ruler at the center of gravity. Keeping the 200 gram and 100 gram mass on the left side of the ruler as
shown in the figure, use the second 100 gram mass to bring the ruler into balance.
Trial Three
1.
Support the ruler at the 60 cm mark. Keeping the 200 gram and 100 gram mass on the left side of the ruler as
shown in the figure, use the second 100 gram mass to bring the ruler into balance.
2
WHAT YOU WILL TURN IN
1. Force Diagram
Draw clearly labeled force diagram showing all of the forces acting on the ruler. Only do this for Trial One. Be
sure to include the force of the hinge and the weight of the ruler.
2. Torque Diagrams
Draw a clearly labeled force diagram showing all of the torques acting on the ruler. Choose the hinge as your
pivot point and be sure to include the torque provided by the weight of the ruler. Do this for all three trials
3. Torque Calculations
Show your calculations for each of the three trials that indicate that the sum of all of the torques is zero ( = 0).
3
Parallel Forces and Equilibrium
PROCEDURE
6. Determine the mass of a meter stick and the two
supporting clamps. If you are using string rather
than clamps, simply determine the mass of the
meter stick. We will assume that the center of
mass at the 50 cm mark.
7. Hang two spring balances 80 cm apart. Use
string to secure them to the top bar. Attach them
to a meter stick at the 10 cm and 90 cm marks
using fishing line or string.
8. Determine the mass of a small mass.
9. Attach the mass with fishing line or string at the
50 cm mark and record the force on each scale.
We will call them Fleft and Fright.
10. Move the hanging mass to the 30 cm mark and
repeat step 4.
11. Move the hanging mass to the 75 cm mark and
repeat step 4.
Data Table
The data table is on the back of this sheet.
Calculations
1. Fill in the second section of the data table by
calculating the weights (W=mg) and total forces
as shown. Is the sum of all forces (F) zero or
nearly zero?
2. Complete a force diagram that shows all of the
forces on the ruler.
3. To complete the third section of the data table,
choose the 10 cm mark, the position of the left
spring scale, as the pivot point. This will
simplify the calculations.
4. Now calculate the torque values using =Fr.
Then calculate the total clockwise torque, total
counterclockwise torque, and the difference as
shown.
5. Complete a torque diagram (similar to the force
diagram) that shows all of the torques on the
meter stick.
4
Data Table
Hanging mass at 50 cm
Hanging mass at 30 cm
Hanging mass at 75 cm
Mass of meter stick
Mass of hanging mass and
hanger
Fleft
Fright
Checking F=0
Weight of meter stick
Weight of hanging mass and
hanger
Total downward weight
(Fdown)
Total upward forces =Fl+Fr
(Fup)
Difference between Totaldown
and Totalup
Checking =0
Distance from pivot pt. to
center of mass of ruler
Distance from pivot pt. to
hanging mass
Distance from pivot pt. to right
spring scale
Torquemeterstick
Torquehanging mass
Total clockwise torque (clock)
Total counterclockwise
torque (counter)
Difference between clock and
counter
WHAT YOU WILL TURN IN
4. Data Table
5. Force Diagrams
A clearly labeled force diagram showing all of the forces acting on the ruler for all three trials.
6. Force Calculations
Show your calculations that indicate that the sum of all of the forces is zero (F = 0).
7. Torque Diagram
A clearly labeled force diagram showing all of the torques acting on the ruler.
8. Torque Calculations
9. Show your calculations that indicate that the sum of all of the torques is zero ( = 0).
5
Reflection Lab
Materials
Flat Mirror
Light Source
Convex Mirror
Protractor
Concave Mirror
Paper clip or other standing items
Part One: Flat Mirror
1. Place the flat mirror on a piece of paper. Draw a line across the paper to indicate the plane of the mirror.
2. Using the light source, mark the angles of incidence and reflection for at four angles. It is very important to only
rotate the light source (do not move it). Make a mark on the paper to indicate the light source and to keep it from
moving. See Figure 1. to help you.
3. When you are done, measure these angles using a protractor.
4. Using the reflected rays you drew, continue them past the line of the mirror to determine the image distance.
How close in value were the object (s) distance and the image distance (s’).
5. Calculate a percent error using the object distance as your accepted value.
Figure 1.
Part Two: Concave Mirror
1. Place the concave mirror on a piece of paper. Draw a line across the paper to indicate the curve of the mirror.
2. Place a paper clip or golf tee about 5 cm in front of the mirror. Mark its position and draw a line across the paper
as shown in Figure 2.
3. Getting down to the level of the table, place another golf tee so that it is directly in line with both the original tee
and the reflection. Mark its position.
4. Using your ruler, trace a perpendicular line to the mirror, and then an angled line between the two marks and the
mirror.
5. Repeat this procedure until you are able to determine the focal length (f) of the mirror. Does this mirror produce a
real or virtual image?
6. Using a light source, measure the focal length for comparison.
7. Calculate a percent error using the focal length from the light source as your accepted value.
Figure 2.
6
Part Two: Convex Mirror
1. Repeat the same steps that you did with the concave mirror.
2. Using the reflected rays you drew, continue them past the line of the mirror to determine the focal length.
3. Using a light source, measure the focal length for comparison.
4. Calculate a percent error using the focal length from the light source as your accepted value.
Figure 3.
What you will turn in:


Neatly recopy your figures onto a separate piece of paper. You may wish to scale them down. DO NOT
SIMPLY TURN IN THE ORIGINALS.
Under each figure, provide a bulleted list explaining the most important points about that section of the
experiment. Include measurements and your percent error calculations.
You may use Power Point to design slides (1 or 2 per section). The best ones may be laminated and showcased in the
classroom for future students. Your path to fame is before you.
7
Snell’s Law
Materials
Refraction tank
Light source
Protractors
Snell’s law relates the index of refraction of a substance to the angle of refraction. Mathematically it is
expressed as:
In our lab, we will consider air to be substance one. It has an index of refraction n1 = 1.00.
Procedure
Using a refraction tank or optical dish, measure the angles of incidence and angles of refraction for a
beam of light as it enters water. Be sure to measure at many angles as is reasonable, and record them in a chart
as shown below.
If time permits, repeat the experiment for a second liquid such as ethanol or a clear soda.
Construct a graph of
. How does this relate to the standard
equation?
What will the value of the slope tell you? Note: you must use the graph to determine n2, not your individual
trials.
Suggested headings for data table
1
2
sin 1
What You Will Turn In
1. Data Table
2. Graphs
3. Calculation of
for the liquid(s) tested
4. Percent error (for water and any other liquid tested)
sin2
8
9
Lenses Lab 1
In this lab, you will determine the focal length of several different lenses, using three different methods.
The third method, using a light ray box, will serve as the accepted value.
To calculate the focal length, use the formula:
Materials
Meter Sticks
Screen holder
Stands
Pencil
Lens holders
Pencil holder
Lenses
Ray Box
Index Cards
Procedure
Part One
Set up your optical bench as shown in Figure 1. Adjust the screen and/or the lens until you just get a
sharp image on the screen. Measure and record the image distance (di). Since the window was very far away
from the screen, we will assume the object distance (do) is infinity.
Repeat this for the other lens as well.
Figure 1.
DATA TABLE 1.
Lens
Large Lens
di
do
f
Small Lens
Part Two
Set up your optical bench as shown in Figure 2. You may need to adjust the height of the pencil so that
the sharpened tip is visible on the screen. The pencil should be about 16-18 cm from the lens. Adjust the
screen and/or the lens until you just get a sharp image on the screen. Measure and record the image distance
(di) and object distance (do).
Repeat this for the other lens as well.
10
Figure 2.
DATA TABLE 2.
Lens
Large Lens
di
do
f
Small Lens
Part Three: Determining the Accepted Focal Length
Place the ray box on a notebook, and some white paper in front of the ray box on the lab bench. Now
place both of your lenses in front of the ray box and measure the focal length. We will use this focal length as
our accepted value.
Focal Length of Large Lens ________
Focal Small of Large Lens
Figure 3.
Calculations
Calculate the percent error for the large and small lenses for Parts One and Two.
________
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Lenses Lab 1: Report Sheet
Compiled Data Table
Lens
di
Part One
do
f
Percent Error
di
Part Two
do
f
Percent Error
Large Lens
Small Lens
Lens
Large Lens
Small Lens
Percent Error (show your calculations below)
Ray Tracing (Show a ray tracing for a convex lens)
12
Abstract
In a paragraph, discuss the following points:





What were you trying to measure, and what methods did you use?
How accurate were your results? Be sure to support your answers with numbers.
What limitations or sources of error may have been present in your lab work?
In what ways could these limitations be minimized or eliminated?
How could this experiment be extended ?
13
Microscope/Telescope Lab
Materials
Meter Sticks
Stands
Lenses
Lens holders
Index card
Card holder
Introduction
In this lab, you will build a working microscope and telescope. You will observe whether the
resulting images are upright or reversed, and estimate the magnification. Let’s start with the
microscope.
The Microscope
1. Set up you meter stick stand as shown in Figure 1. Be sure that the side of the index card
with the blue lines is facing you.
2. Adjust the lenses until you just see a clear image with your eyes. Try to place your eye at
about the zero mark on the meter stick.
3. Record the values on the meter stick for the two lenses and the index card.
4. Estimate the magnification of the lenses from the spacing of the lines. Record whether
the image is upright or upside down.
5. Use a ray box to measure the focal lengths of the lenses. How do these focal lengths
compare with the measurements from the meter stick?
Figure 1.
The Telescope
1. Set up you meter stick stand as shown in Figure 2. Be sure that the blank side of the
index card is facing the window. It will serve as our viewing screen
2. Adjust the lenses until you just see a clear image on the index card.
3. Record the values on the meter stick for the two lenses and the index card.
4. Record whether the image is upright or upside down.
14
5. Use a ray box to measure the focal lengths of the lenses. How do these focal lengths
compare with the measurements from the meter stick?
6. Now substitute a concave (diverging) lens for the small lens. Move the lens until a clear
image is formed on the screen.
7. Record whether the image is upright or upside down.
8. Use a ray box to measure the focal lengths of the lenses. How do these focal lengths
compare with the measurements from the meter stick?
Figure 2.
What you will turn in:
1. Data Table
Type of
instrument
Focal
length 1
Focal
length 2
do
di1
di2
Upright or
inverted?
2. Ray diagram of the three set-ups (you may need to reference a book to help you draw
these.)
3. How did adding the concave (diverging) lens to your telescope affect the image? How
did it affect the distances between the lenses? Were they longer or shorter than the focal
lengths?
4. Why do many telescopes use mirrors rather than lenses?
5. What are some differences between terrestrial and astronomical telescopes?
15
NAME:
Materials:
two balloons
Coulombic Forces Lab
string
protractor
electronic balance
ruler
Procedure
1. Blow up two balloons to approximately the same volume. Determine the
mass of both of the balloons, and calculate the average mass.
2. Suspend the two balloons from the stand. Make sure the strings are of
equal length. Measure the length of the string (L) to the center of the pith
ball.
3. Rub each balloon on your hair until it picks up charge. Rub the balloons
again to try to get the largest separation possible.
4. Measure the angle (2) that the two strings make with each other at the
point of origin. Divide the angle in half to calculate . You may wish to
try rubbing the protractor on your hair to give it a negative charge if the
balloons are attracted to the protractor.
Calculations
1. Sketch a free body diagram for each pith ball showing all forces acting on each while suspended.
2. Determine the total distance, r, between the balloons.
3. Using the following equation, determine the charge, q, on each balloon (we will assume they each have
the same charge):
4. Calculate the number of excess electrons on each pith ball while each was suspended.
5. Using the knowledge the Fx = 0 and Fy = 0, see if you can derive the formula shown above.
16
NAME:
Ohm’s Law Lab
MATERIALS
Power supply
Wires
Resistance Box
Triple Scale Anmeter
SAFETY
 Keep the power supply unplugged when setting up and tearing down the experiment.
 Have your instructor check our circuit before you turn it on.
 Keep all fingers away from exposed metal in the circuit at all times.
PROCEDURE
Part One
1. Connect the circuit as shown below in Figure 1. Use the following initial settings:
Voltage = 1.5 V
Resistance = 30 
Connect the cord to the 50 mA peg
Figure 1.
2. Have your instructor check your setup before plugging in the power supply.
3. Now turn on your power supply and record the current on the anmeter. Remember we are reading the 50 mA
scale.
4. Turn the “10’s” knob on the resistance box to increase the resistance as shown in Data Table 1. Record the
current. When you have finished recording your data, turn off the power supply.
Data table 1.
Resistance ()
30
40
50
60
70
80
90
Current (mA)
Current (A)
1/Resistance (-1)
17
Part Two
1. You will use the same circuit as in Part One. Use the following initial settings:
Voltage = 1.5 V
Resistance = 240 
Connect the cord to the 50 mA peg
2. Have your instructor check your setup before plugging in the power supply.
3. Now turn on your power supply and record the current on the anmeter. Remember we are reading the 50 mA
scale.
4. Turn the “10’s” knob on the resistance box to increase the resistance as shown in Data Table 2, and record the
current. When you have finished recording your data, turn off the power supply. Reset the voltage knob to 1.5 V
and turn the power supply off.
Data table 2.
Voltage (V)
Current (mA)
Current (A)
1.5
3.0
4.5
6.0
9.0
12.0
Calculations and Graphs
Part One
Ohm’s law is V = IR, voltage equals current X resistance.
1. Solve Ohm’s law for current, I.
2. On a graph, plot the current (I) in Amperes versus 1/Resistance (1/R), in -1. Current will be on the y-axis.
3. Calculate the slope. What term is the slope equal to?
4. Label this graph as Graph 1., and give it an appropriate title.
Part Two
1. On a second graph, plot the voltage (V) in Volts versus current(I) in Amperes. Voltage will be on the y-axis.
2. Calculate the slope. What term is the slope equal to?
3. Label this graph as Graph 2., and give it an appropriate title.
Error Analysis
Part One
The accepted value for voltage is 1.5 V. Calculate the percent error using your slope from Graph 1. as the experimental
value.
Part Two
The accepted value for resistance is 240 . Calculate the percent error using your slope from Graph 2. as the
experimental value.
18
19
NAME:
Circuit Puzzles Lab
In this lab, you will set up several circuits and observe how the brightness of the bulbs changes. To help you
get accurate data in a safe fashion, remember the following points.




Always start the power supply at 1.5 V. Only increase it if you can’t see the bulbs.
Switch off the power supply when changing the circuit. This will prevent any shocks.
Use the same style of bulbs for the entire experiment.
If you are uncertain whether a bulb works, test it alone at 1.5 V.
Set up the following circuits and observe the brightness of the bulbs. Label your bulbs as A, B, and C for easy
reference. In the last two boxes, you should design a circuit of your own.
Circuit
Observations
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21
Resistivity() of Graphite Lab
Procedure
1. Obtain a pencil and measure the diameter of just the graphite.
2. Sharpen both ends of the pencils and measure the total length of the graphite.
3. Set up a circuit with the power source, pencil, and an anmeter in series. Turn on the power source to 1.5 V and
record the voltage and current. Calculate the resistance of the graphite using Ohm’s Law, V=IR.
4. Turn off the power and remove the pencil from the circuit. Sharpen the pencil a little and measure the new length.
5. Replace the pencil in the circuit and measure the voltage and current again.
6. Repeat this procedure until you have at least 5-10 data points.
Data Table 1.
Diameter (mm)
Length (m)
Voltage (V)
Current (A)
Resistance ()
Graphing
We wish to construct a graph to determine the resistivity, r, of graphite using the equation:
If we plot resistance, R, on the y-axis, what value should be plotted on the x-axis so that the slope is equal to the
resistivity? Be sure all measurements are in meters.
What you will turn in
 Circuit diagram
 Data Table
 Graph
 Calculation of slope and Percent Error. The accepted resistivity of graphite is 800 X 10-6  m
22
NAME:
What is a Capacitor Lab
Safety
Check all completed circuits with the instructor before turning on the power.
Materials
Power source
Capacitor
Stopwatch
620  Resistor (blue-red-brown-gold)
Cords
Knife Switch
LED Light (1.6 V)
220  Resistor (red-red-brown-gold)
1.1 k Resistor (brown-brown-red-gold)
Procedure
1. Obtain the materials listed above.
2. Set up the circuit as shown in Figure 1. Use the 220 
resistor. Be sure that the negative lead of the capacitor
goes to the negative lead of the power source. The arrow
on the capacitor points to the negative lead. Also, the
negative lead of the LED is the shorter wire.
3. Be sure the switch is open.
4. Have your instructor inspect your circuit.
5. Set the power source to 9 V, then turn it on for at least
30 seconds to charge the capacitor.
6. Turn off the power source
7. Flip the switch to the light bulb, and time how long the
bulb remains lit.
8. Repeat this for a total of four trials, and record the
average time in Data Table 1.
9. Repeat steps 2-8, but this time use the 620  resistor.
10. Repeat steps 2-8, but this time use the 1.1 k resistor.
Figure 1.
Data Table 1.
220 
LED “On” time 1
LED “On” time 2
LED “On” time 3
LED “On” time 4
Average LED “On” time
RC
620 
1.1 k
23
What you will turn in:
1. Neatly Recopied Data Table
2. Answer the following questions
a. What is the relationship between the RC constant for the circuit, and the amount of time that
LED was lit?
b. Were you able to observe any relationship between the resistance and the brightness of the bulb?
c. What values could we have measured while we were using these circuits? Be as specific as
possible in your answers, referring back to the chapter and lecture notes on RC circuits.
3. Suppose you have a capacitor of unknown capacitance. You have a 780  resistor and a 1.6 V LED (It
will go out once the voltage drops to 1.6V or below). You also have a 9-V battery and a voltmeter.
Describe how you could determine the capacitance. Be sure to reference any needed equations.
24
NAME:
MATERIALS
Power supply
Resistance Box
Time Constant of an RC Circuit Lab
Wires
Mini-bulbs
1 F capacitor
Voltmeter
25,000F capacitor
Stopwatch
PROCEDURE
Connecting the Circuit
The circuit in this lab is a bit complicated, so we will set it up step by step. Do not plug in or turn on the power supply
until your instructor has checked your circuit.
Set up the following basic RC circuit with a mini-lamp (Bulb 1). Use the 4.5 volt setting on the power supply, but do not
turn the power supply on yet. For now, use R= 10  and C = 1 F. The negative side of the capacitor is the side with the
stripe.
Observing Bulb 1
1. Now have your instructor check your circuit.
2. Turn on the power supply to the 4.5 V setting and observe the appearance of Bulb 1 over time (about 30 seconds).
Observing Bulb 1
1. After about 30 seconds, turn off the power supply.
2. Close the knife switch to discharge the capacitor. You must wait until Bulb 2 goes completely out.
3. Observe the brightness of the Bulb 2 over time.
4. Once Bulb 2 has completely dimmed, remove Bulb 1 from the circuit.
Measuring the Time Constant
1. After waiting about a minute (or until Bulb 2 goes completely out), open the knife switch.
2. Turn on the power supply (to 4.5 V) and measure the time it takes to reach 3 V on the voltmeter.
3. After 3 V is reached, turn off the power supply.
4. Close the knife switch to discharge the capacitor through Bulb 2. Wait until Bulb 2 goes completely out.
5. Open the knife switch, and repeat this procedure 3-4 times. Report the average time in the data table.
Measuring other Time Constants
1. Unplug the power supply.
2. Rewire the circuit using R = 220  and C = 25,000 F.
3. Now repeat the experiment, measuring the time to reach 3 V. Be sure to discharge the capacitor through Bulb 2
by closing the knife switch between trials.
4. Report the average time of your 3-4 trials in the data table.
5. Rewire the circuit using R = 100  and C = 25,000 F and repeat the experiment.
25
Data Table
Voltage (Vmax)
Resistance ()
Capacitance (F)
time(s)
theoretical(s)
experimental(s)
Percent Error
Range of t values (s)
Trial One
4.5
10
1
Trial Two
4.5
220
0.025
Trial Three
4.5
100
0.025
Calculations Help
1. Calculate the theoretical value of the time constant using: theoretical = RC.
2. Calculate the experimental value of the time constant, experimental , using the following formula:




V=3V
Vmax = 4.5 V
t = the time you measured until the voltage reached 3 V
You are solving for RC
What you will turn in (On a separate piece of paper)
1. Neatly recopied data table
2. Sample Calculations
3. Questions
a. Describe the brightness of Bulb 1 over time. Explain why it did not glow at a constant brightness.
b. Describe the brightness of Bulb 2 over time. Explain why it did not glow at a constant brightness.
c. Why was the second loop with the knife switch and Bulb 2 necessary in this circuit?
d. How closely did your experimental and theoretical time constants agree?
e. Explain how an RC circuit can be used as a timer in a circuit.
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43
NAME:
Kirchoff’s Rules Lab
Materials
Resistance boxes/Rheostat
Wire (18 ga)
Voltmeter (0-3 V)
Ammeter (0-1 A)
DC power source (6 V)
Knife switch
Procedure
Part One: Determining the Theoretical Values of I1, I2, I3
1.
2.
We will set up the circuit that is shown to the right. We
will use resistance boxes or resistors rather than light
bulbs.
Before setting up the circuit, use Kirchhoff’s rules to
calculate the theoretical values of I1, I2, and I3. We will
use the following values of:
V=6V
R1 = 10 (Use resistance box)
R2 = 20 (Use adjustable rheostat)
R3 = 20 
3.
Record your theoretical values in the data table.
Part Two: Determining the Experimental Values of I1, I2, I3
1. Set up the circuit as shown. Have your instructor check your circuit before plugging in the power supply.
2. Close the switch and record the values of I1, I2, and I3.
Part Three
1. If time permits, repeat the experiment using the following voltage and resistance values:
V=6V
R1 = 5 
R2 = 10 
R3 = 20 






V=6V
R1 = 10 
R2 = 20 
R3 = 10 
Data Table Format
Values Used
Potential (V)
R1 ()
R2 ()
R3 ()
Theoretical
I1
I2
I3
Actual
Percent Difference
44
NAME:
Resistance Coils Lab
Materials
Resistance coil
Alligator clip wires
Voltmeter (0-3 V)
Ammeter (0-1 A)
DC power source (6 V)
Knife switch
Procedure
1. We will be measuring the resistance of several long wires, which are wound on coils for convenience. The
resistance coil is shown below. Note that we can measure the resistance of each coil by attaching our wires to
different posts.
Resistance Coils
Our experimental setup
2.
Set up the experiment as shown. You may wish to use the on/off switch of your power supply rather than a knife
switch. SET THE POWER SUPPLY TO THE LOWEST VOLTAGE SETTING. Be sure to have your instructor
check your setup before you turn on the power.
3. Record the current reading for each coil. The voltage will be the setting on the power supply. Alternately, you be
asked to record the voltage drop across each resistance coil.
4. Turn off the power supply and move on to the next coil. Repeat until you have measured current and voltage for
each of the coils.
Data Table
Coil 1
Coil 2
Coil 3
Coil 4
Coil 5
Voltage
Current
Experimental Resistance
Metal/Alloy
Length (m)
Gauge
Diameter (mm)
Radius (m)
Area (m2)
Resistivity (-m)
Theoretical Resistance
Percent Error
Calculations
1. To calculate the Experimental Resistance, use Ohm’s Law: V = IR
2. Look up the wire’s gauge and diameter on the chart on the back. Calculate the radius in meters, and the area of
the wire using A = r2.
3. To calculate the Theoretical Resistance, use: R = l/A
R = resistance ()
45
 = resistivity (-m) (see chart in book)
l = length (m)
A = area of wire (m2)
AWG gauge
Conductor
Conductor
Ohms per km
Diameter Inches Diameter mm
1
0.2893
7.34822
0.406392
2
0.2576
6.54304
0.512664
3
0.2294
5.82676
0.64616
4
0.2043
5.18922
0.81508
5
0.1819
4.62026
1.027624
6
0.162
4.1148
1.295928
7
0.1443
3.66522
1.634096
8
0.1285
3.2639
2.060496
9
0.1144
2.90576
2.598088
10
0.1019
2.58826
3.276392
11
0.0907
2.30378
4.1328
12
0.0808
2.05232
5.20864
13
0.072
1.8288
6.56984
14
0.0641
1.62814
8.282
15
0.0571
1.45034
10.44352
16
0.0508
1.29032
13.17248
17
0.0453
1.15062
16.60992
18
0.0403
1.02362
20.9428
19
0.0359
0.91186
26.40728
20
0.032
0.8128
33.292
21
0.0285
0.7239
41.984
22
0.0254
0.64516
52.9392
23
0.0226
0.57404
66.7808
24
0.0201
0.51054
84.1976
25
0.0179
0.45466
106.1736
26
0.0159
0.40386
133.8568
27
0.0142
0.36068
168.8216
28
0.0126
0.32004
212.872
29
0.0113
0.28702
268.4024
30
0.01
0.254
338.496
31
0.0089
0.22606
426.728
32
0.008
0.2032
538.248
46
NAME:
Light Bulbs in Series Lab
Materials
Small Bulbs and sockets
Wires
Voltmeter
Ammeter
DC power source
Procedure
Part One: Determining the resistance of the light bulb
1.
4.
5.
Set up the circuit as shown. Do not connect the power
supply until your teacher checks your set-up.
Turn on the power supply to 1.5 V. Do not go higher
unless the bulbs do not glow.
Record the voltage and current. Turn off the power
supply.
Part Two: Verifying Ohm’s Law
1.
6.
2.
3.
Set up the circuit as shown below. Do not connect the
power supply until your instructor checks your set-up.
Turn on the power supply to 1.5 V. Do not go higher
unless the bulbs do not glow.
Record the voltage and current. Turn off the power
supply.
If time permits, place a third bulb in series and measure
the voltage and current. Be sure to connect the
voltmeter across all three bulbs.
Data Table
One Bulbs
Two Bulbs
Three Bulbs
Voltage
Current
Resistance (experimental)
Resistance (theoretical)
Percent Error
Calculations Help
To calculate the theoretical resistance, we will assume that the resistance of all the bulbs is the same. To calculate the
theoretical resistance of two or more bulbs in series, use:
Rtheo = R1 + R2 + R3
47
NAME:
Materials
Small Bulbs and sockets
Wires
Light Bulbs in Parallel Lab
Voltmeter
Ammeter
DC power source
Procedure
Part One
1.
2.
3.
Set up the circuit as shown. Do not connect the power
supply until your teacher checks your set-up.
Turn on the power supply to 1.5 V. Do not go higher
unless the bulbs do not glow.
Record the voltage and current. Turn off the power
supply.
Part Two
1.
2.
3.
4.
Set up the circuit as shown below. Do not connect the
power supply until your instructor checks your set-up.
Turn on the power supply to the voltage suggested by
your teacher.
Turn on the power supply to 1.5 V. Do not go higher
unless the bulbs do not glow.
If there is sufficient time and materials, add a fourth bulb
to the circuit and measure voltage and resistance.
48
Data Table
Two Bulbs
Three Bulbs
Four Bulbs
Voltage
Current
Resistance (experimental)
Resistance (theoretical)
Percent Error
Calculations Help
To calculate the theoretical resistance, we will assume that the resistance of all the bulbs is the same. We will use the
resistance of a single bulb that was determined in the previous lab. To calculate the theoretical resistance of two or more
bulbs in series, use:
1
1 + 1 + 1 + 1
Rtheo = R1 R2 R3 R4
49
NAME:
Materials
Magnets
Introduction to Magnetism Lab
Paper
Compasses
Wire
Power Supply
20 Resistor
Procedure
Part 1: Permanent Magnets
1. Place a bar magnet on a piece of paper as shown in Figure 1. Trace the outline of the magnet onto the paper,
labeling the north and south poles of the magnet.
2. Place a small compass right next to the magnet. Draw a small arrow that shows the direction of the north end of
the magnet needle (usually the red end).
3. Move the magnet all the way around the magnet, drawing an arrow every few centimeters. Note that the arrow
flips direction at a certain point.
4. Move the magnet about two centimeters out from the magnet and draw arrows all the way around the magnet
again. Do this several times, until the magnet no longer moves the needle of the compass (usually around 10 cm).
5. Gently remove the magnet from the paper. Place the compass in one corner of the paper and note the direction of
the earth’s north pole.
6. Repeat this procedure with a horseshoe magnet if one is available.
Figure 1.
Part Two: Straight Wire Electromagnet
1. With the power supply off, connect a long wire to the power supply as shown in Figure 2. Be certain that a 20 W
resistor (or another value suggested by your teacher) is present in the circuit. Lay the wire across a piece of paper
as shown.
2. Note the direction of the earth’s north pole on your paper.
3. Turn on the power supply and map the magnetic field just as you did with the bar and horseshoe magnets. Turn
off the power supply when you are done.
Figure 2.
50
Part Three: Coil Electromagnet
1. With the power supply off, connect a long wire coil to the power supply as shown in Figure 3. Lay the coil across
a piece of paper as shown. You may need a resistor in your circuit. (check with your instructor)
2. Note the direction of the earth’s north pole on your paper.
3. Turn on the power supply and map the magnetic field just as you did with the bar and horseshoe magnets. Turn
off the power supply when you are done.
Figure 3.
What You Will Turn In:
1. Drawings of Magnetic Field.
2. Answer the following questions:
a. How do your diagrams compare with those that you expected?
b. How does the strength of the magnetic field of the coiled wire compare with the straight wire?
c. How does the shape of the magnetic field of the coiled wire compare with the straight wire?
d. What “other magnet” might affect your readings? Is there any way to get rid of the effect of this “other
magnet”?
51
NAME:
Materials
22 ga. wire
28 ga. wire
Electromagnetic Induction Lab
Galvanometer 25 mm test tubes
Bar magnets
18 mm test tubes
String
Procedure
Part 1: Investigate Induction
1.
2.
3.
4.
5.
Wrap about 100 turns around a test tube large enough for a bar
magnet to pass through. This coil may already be prepared for you.
Connect the ends of the coil to a galvanometer as shown in Figure 1.
Quickly thrust the N-pole of a magnet into the coil and record your
observations.
Remove the magnet quickly and record your observations.
Try different speeds to find the one that gives the maximum
deflection of the galvanometer needle.
Now try the S-pole of the magnet and record your observations.
Figure 1.
Part Two: Make a Simple Transformer
1.
2.
3.
Connect the leads of the primary (smaller) coil to a power supply.
Be sure to include a knife switch or make sure that the power
supply is unplugged and off.
Connect the leads of the secondary coil to a galvanometer.
Slip the primary coil inside the secondary coil as shown in Figure 2.
Make the following observations about the deflection of the
galvanometer needle:
-When the current first flows through the primary coil
-When the current has been on for a few seconds
-When the current is suddenly interrupted
-When the magnitude of the current is varied (change the
resistance)
-When the current’s direction is reversed
-When an iron rod is placed inside the primary coil
Figure 2.
52
Part Three: Make a Simple Generator
1.
2.
3.
4.
5.
6.
Wrap about 20 turns of 28 ga insulated wire into a coil as shown in
Figure 3. Leave long tails at the end of each loop, and secure the
loop with string or electrical tape.
Connect the leads of the loop to a galvanometer.
Place magnets as shown around the loop. The loop of wire will
need to twist inside the loop, so you may wish to place the magnets
on books or metal blocks.
Give the coil a quick twist (about 60o) and note the galvanometer
reading.
What happens to the needle if you twist in the opposite direction?
Can you find a position for the loop where turning the coils causes
no deflection?
Figure 3.
What You Will Turn In:
Part 1: Investigate Induction
Experiment
N-pole thrust into coil
Varying the speed of the N-pole
S-pole thrust into coil
Result
Explanation of Results
Part Two: Make a Simple Transformer
Experiment
Current first flows through primary coil
Current has been on for a few seconds
Current is suddenly interrupted
Magnitude of the current is varied
Current’s direction is reversed
Iron rod is placed inside the primary coil
Result
Explanation of Results
Part Three: Make a Simple Generator
Experiment
Twisting the coil about 60o
Twisting the coil in opposite direction
Twisting from different starting angles
Explanation of Result
Result
53
NAME:
Speed of Sound Lab
54
55
56
NAME:
Simple Pendulum Lab
In this lab, we will experiment with a simple pendulum. A pendulum is much like a playground swing. Imagine timing
how long it takes to complete one entire swing (back and forth). This is called the Period. A swing with a short period
swings very fast. A swing with a long period swings very slowly. Do you think the pendulum will swing faster if the
chain on the swing is longer or shorter?
Materials
String
Stopwatch
Mass
Stand for pendulum
Procedure
Part One
1. Tie a mass to the end of the pendulum.
2. Hang the pendulum from a stand or have one lab partner hold the pendulum steady. Measure the length of the
pendulum. Measure from the pivot point to the center of the mass hanging from the pendulum.
3. The other lab partner should release the pendulum and begin timing.
4. Time how long it takes for the pendulum to complete twenty entire swings (back and forth). Record your data
below in the Trial One column.
5. Now wrap your string around the stand a few times to decrease the length of the pendulum. Repeat the procedure
several times, decreasing the length of the pendulum each time. Keep the release height constant, and at about
15o.
Part Two
1. Now you will repeat the procedure. However, this time, you will keep the length of the string constant.
2. This time you will vary the masses on the end of the string.
Data Table 1
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Mass on the pendulum
(kg)
Length of the
pendulum (m)
Square root of Length
of pendulum (m1/2)
Time for 20 swings (s)
Time for 1 swing
(Period) (s)
Data Table 2
Mass on the pendulum
(kg)
Length of the
pendulum (m)
Time for 20 swings (s)
Time for 1 swing
(Period) (s)
57
Graph
1. Graph 1: Your x-axis will be the Length of the pendulum. Your y-axis will be the Period (Time for 1 swing) in
seconds. Note that we will not use the “Time for 20 swings” on any of our graphs.
2. Graph 2: Your x-axis will be the square-root of the Length of the pendulum. Your y-axis will be the Period
(Time for 1 swing) in seconds.
3. Graph 3: Your x-axis will be the mass the pendulum. Your y-axis will be the Period (Time for 1 swing) in
seconds.
Calculations
1. Calculate the slope of the graph that is most linear and increasing.
2. To calculate a percent error, we will use as the accepted value. Use the slope of the graph that was most linear.
Additional Questions
a. Does the period of a pendulum vary with the mass or the length of the pendulum. How do you know.
b. Which graph was linear? What does the slope represent?
c. Can you determine the equation that relates the period of the pendulum(y) to the length or the mass (x).
58
NAME:
Physical Pendulum Lab
In this lab, we will experiment with a physical pendulum. Our physical pendulum will be a meter stick whose pivot is
near the top of the ruler. Your goal is to measure the period for the physical pendulum and compare it to theoretical value.
The theoretical value will be calculated using the formula. In this lab, you will design the procedure and the data table.
Materials
String
Stopwatch
Meter stick
Stand for pendulum
What you will turn in:
1. Abstract – In your second paragraph, discuss other common objects that could be tested as a simple pendulum.
2. Data Table
3. Calculations and Error Analysis (Percent error and range of the measured values for the period)
A sample abstract for a simple density experiment might read:
"The density of a sample of aluminum was determined and compared to the literature value of 2.70 g/mL. The
volume was measured using water displacement in a graduated cylinder, and the mass was measured on an electronic
balance. The density was calculated using the formula: density=mass/volume. The average experimental density of 2.65
g/mL agreed with the literature value with a percent error of 1.9%. The four trials had a precision of 0.13 g/mL. These
results indicate that this is an effective method for determining the density of a solid sample of metal.
If the lab were to be repeated, students should carefully slide the metal pieces down the side of the graduated
cylinder. This would prevent any splashing that would lower the recorded volume of the sample. A second way to
improve the accuracy would be to first melt the zinc pieces into a smooth sample. The zinc pieces had a number of holes
and pits which could have trapped air bubbles. This would increase the recorded volume of the sample. A third way to
improve the experiment would be to dry the metal pieces between trials with a hair dryer to drive off any excess water."