MY PHYSICS S.B.A
Experiment #1
Title: Reflection
Aim: To investigate the relationship between the angle of incidence and the angle of reflection.
Theory: Reflection is said to occur when a light ray is bounced off a reflective surface. To measure the
angles, the protractor is placed on the normal in line with the 900 line on the protractor and read from
the 900 to the base line. The precautions associated with this experiment are to place the mirror on the
line drawn and protractor on 900 line.
Variables: manipulating variable: angle of incidence (c) responding variable: angle of reflection (r)
Apparatus: a sheet of paper, tacks, 4 optical pins, optical board, mirror, mirror support (block),
protractor, sharp pencil.
Diagram:
Method: a sheet of paper was tacked onto a board. A mirror line was then drawn close to the edge of
the paper. A protractor was used to draw in a normal in the midst of the mirror line. The protractor was
used again to draw lines at the angle of incidence from 150, 300,750. The mirror was then placed on the
line so that the silver edge was on the line drawn. Two pins were placed on the 1ST line of incidence (150)
Pin A was close to the edge of the paper. The images of the pin of pin A & B close to the mirror. A fourth
pin (D) was paced at the edge of the paper in line with pin (C) and the images of pin A & B. All pins were
removed and an (X) was placed over the hole left from the pins. The mirror line was extended and a line
was drawn in to indicate the path of the reflected ray. The protractor was then used to measure the
angle of reflection results were taken of it and its corresponding angle of incidence was repeat was done
to all the other incidence line.
Results: Table showing angle of incidence and reflection
Ө ἱ l0±l0
10
20
30
40
50
60
Ө rl0±l0
10
20
30
40
50
60
Analysis: Reflection is the throw back of rays when they have reached a boundary or reflective surface.
There are two laws governing reflection they state that:
1. The angle of incidence and angle of reflection are equal. This was shown when the angle of
incidence and the angle of reflection were measured. All angles were equal.
2. The incident vary, reflected ray and the normal, all lie in the same place. This was proven as the
incidence ray. Reflected ray and the normal could be drawn on a sheet of paper.
Precautions: Plane mirror was held steadily on the sheet of paper. Protractor measurements were taken
accurately. Angles were measured correctly. Lines were drawn correctly to the angles measured.
Causes of error: A parallax error may have occurred with pins (1) and (2) resulting in wrong placement of
pins (3) an error in the protractor reading may have occurred.
Conclusion: the angle of incidence is equal to the angle of reflection: the incident, reflected rays and
normal all lie in the same plane.
Experiment #2
Title: Refraction
Aim: To investigate the relationship between the angle of incidence and the corresponding angles of
refraction for glass
Objectives: Refraction is the bending of rays when travelled from one medium to another
Variables: manipulating: angle of incidence responding: angle of refraction
Apparatus: glass lock, ruler, paper, protractor, four coloured markers, tacks, pencil, board.
Diagram:
Procedures: A sheet of paper was tack onto a board. The glass block was placed in the middle (Center) of
the paper and the outline of it was drawn with a pencil. The protractor was used to draw a normal on
the middle of the long side of the block. The intersection of the normal and the glass block was labeled
as point x. The protractor was use again to measure out and draw lines at the angle of incidence of
100,200, up to 600. On the line two lines were drawn upright, so that the line was close to the block as
possible and line 1 was close to the edge of the paper. The glass block was then replaced. After looking
through the glass block at image 1 and 2 the image of line 1 was directly behind the image of line 2. Line
3 was close to the block so it appears to be in line with images of line 1 and 2. Line 4 was drawn close to
the edge of the paper in line with line 3 and the images of 1 and 2 was placed over the line after line 3
was measured with a protractor and then recorded. The procedure was repeated for all angles of
incidence drawn.
Table of incidence: table showing the relationship between angle of incidence and refraction
Ө ἱ l0±l0
10
20
30
40
50
60
Ө rl0±l0
7
14
19
20
32
38
Sin ἱ
0.1736
0.3420
0.5
0.6427
0.7660
0.8660
Sin r
0.1045
0.2079
0.2923
0.4067
0.4848
0.5446
Precautions: Place protractor on the 900 line. Place glass block in box property.
Sources of Error: systematic error in protractor parallax error in protractor readily and in drawing
emergent ray.
Conclusion: The ratio of the sine of the angle of incidence divided by the sine of the angle of refraction is
a constant shown as the refractive index according to snells law, the refractive index of the glass block is
1.5 which was proven in the experiment.
Experiment #3
Title: Planning and designing (Refraction)
Problem Statement: plan and design and experiment to measure the refractive index of sea water near
the shore
Hypothesis: In sea water, a can appears clearer than it is.
Aim: To measure the refractive index of sea water near the shore
Apparatus: Coin, Ruler, Aquarium, Sea Water,
Diagram:
Method: 1) Set up apparatus as shown in the diagram
2) Use the ruler to locate and measure the distance of the image
3) Record the real depth and apparent depth of the coin
4) Repeat step 2&3 two more times and find the average of the apparent and real depth
5) Use the formula for real depth to find the refractive index apparent depth
Expected Result:
Real Depth
1M
Apparent Depth
1M
Refractive Index
Treatment of results: plot graph of real depth is apparent depth
Precautions: 1) Do not do the experiment on a rocky surface or windy area to prevent observation of
wrong reading of the real and apparent depth
Sources of Error: 1) Incorrect calculation
2) Windy area
3) Reading the ruler incorrectly
Experiment #4
Title: Planning and designing (Pendulum)
Problem Statement: A student propose that the mass at the end of the pendulum will affect the period
of the pendulum
Hypothesis: changing the mass on the string will not affect the time at which it takes for the pendulum
to swing one complete oscillation
Aim: to investigate that the mass at the end of the pendulum will affect the period of the pendulum
Apparatus: stop watch, pendulum bob, and 3 different masses.
Diagram:
Method: 1) set up the apparatus
2) Attach a weight to the string and record the time taken for it to make 20 oscillations
3) Remove the previous weight and add another weight and record the time
4) Repeat step two with a different weight and record the time
5) Record result in appropriate table
Expected Result:
Weights
1st time
2nd time
3rd time
Precautions: pendulum should hang vertical and be securely supported
Sources of error:
1) Draft can cause an interruption in the reading of the pendulum in which it can
increase or decrease it
2) Masses of the weight not being placed on the stand properly
3) Starting the stop watch at the wrong time
Experiment #5
Title: Deformation
Problem Statement: to determine the relationship between applied force and the resulting extension
for a string
Apparatus & Materials: Refort stand, paper clip, painter, six (6) 2g masses, 50cm ruler, steel spring,
beaker (200ml), containing 200ml of water.
Diagram of Apparatus:
Variables: manipulated: mass added: applied force (N)
Controlled: the string
Responded: extension of the spring
Method: the apparatus was set up as shown in the diagram. The reading of the pointer was noted
before adding any weight. This was the initial pointer reading. A single 50g mass was added and the
reading of the pointer was recorded. The difference in the pointer reading between the final and the
initial, gave the extension
of the spring. Another 50g mass was added and the pointer reading was
recorded until the total mass was 300g. The clamp was adjusted to completely immerse the base of the
mass holders in a beaker of water. The new initial reading of the pointer was recorded. The difference
between the pointer readings gave the apparent extension of the string
Result:
Mass Added (g)
Final Reading (cm)
24.4
29
31.4
35.8
39.7
44.5
48.5
0
50
100
150
200
250
300
Extension (cm)
0
5.4
7
11.4
15.3
20.1
24.1
Applied Force (N)
0
0.5
1.0
1.5
2.0
2.5
3.0
Final Reading: 31.5 cm
Initial Reading: 29.9
Apparent Extension: 3 cm
Data Analysis: A graph of force (N) against extension, ἱ, was plotted. Its gradient was then calculated
using the formula
M = (y2-y1)/(x2-x1) = (24.8-12) / (3.5-1.25) = 5.69
According to the graph, the apparent weight of the immersed 50g mass is 0.38N. The relationship
between the applied force and the extension that 1 is proportional to 10. This is in accordance with
Hookes law which states that the extension is directly proportional to the land provided that the elastic
limit was not exceeded.
Precautions: ensure the environment is constant in order to get correct results.
Sources of error:
1) Inherit error in 50cm ruler
2) Parallel error in reading scale
Conclusion: A straight line graph through the origin indicates that the extension of t he spring is directly
proportional to the stretching force that was applied to it.
Experiment #6
Title: To find the density of an irregular shaped object (Stone)
Apparatus: Stone, measuring cylinder, water, balance
Diagram:
Procedures: The mass of the stone was found by using the balance. The stone was then placed in a
measuring cylinder containing a known Volume of water. The new volume was recorded. The procedure
was repeated until a consistent answer for the volume obtained.
Result:
Mass of Stone
13.35
13.35
13.35
Initial volume of water (cm3)
50
40
70
Final volume of water (cm3)
55
46
76
Data Analysis: The density of the stone was calculated
Density = mass/volume = 13.35/5 = 2.67g/cm3
Precautions: (1) Ensure that the balance is zeroed
(2) Ensure that the measuring has water
Sources of error: (1) The balanced was not placed on a surface
(2) The reading were not properly taken
Conclusion: the density of the stone was found to be 2.67g/cm3
Density of stone g (cm3)
13.35/5=2.67
13.35/6=2.23
13.35/6=2.23
Experiment #7
Title: Heat
Apparatus: To find the specific heat capacity of a metal using the method of mixtures.
Diagram:
Procedures: The mass ms, of the metal was found and recorded using a balance. A string was tied to the
metal then placed in a beaker with water where the water was allowed to boil for at least 5 minutes.
The mass ms of the liquid placed in the Styrofoam cup was found by using the balance to find the mass
of the cup alone, and the mass of the cup and the liquid. The initial temperature q, of the liquid in the
cup was recorded. The metal was transferred as quickly as possible from the beaker to the Styrofoam
cup with liquid and string began. The highest temperature, 0, of the liquid obtained after, the metal
placed in the Styrofoam cup was recorded.
Data Analysis: The transfer of the metal should be done quickly as heat may be lost to the surrounding.
Mixing causes the higher temperature to flow to the lower temperature until both substances are at the
same temperature. The Styrofoam cup is a good choice to use in this experiment as the material making
it up is a good insulator which means heat cannot be conducted by it.
Heat energy Joined by liquid= heat energy lost by metal.
Formula =
.: MM X CM X
Tm = M2 X C2 X
T2
0.1KG X CM X (100 -34)J = 92.82 X 4200J X (34-28)
0.1KG X CM X 66J = 0.0928 X 4200 X 6
CM = (0.0928 X 4200 X 6)/ 0.1KG X 66J
CM = 354.33 JKg-1K-1
The assumption is not true as most of the heat given off is loss to the atmosphere before it reaches the
liquid.
Precautions: (1) Do not put your hands near the flame
(2) Ensure that the metal is transfer quickly
Sources of error: (1) Thermometer might not be read correctly
(2) The metal was not transfer quickly hence heat may be lost
Conclusion: The specific heat capacity of a metal was found to be 354.33 JKg-1K-1
By using methods of mixture.
Experiment #8
Title: planning and Design (Heat)
Problem and statement: plan and design and experiment to investigate how concentration (amount of
dissolve in liquid) affects the specific heat capacity of a liquid.
Aim: To investigate whether the concentration of a salt solution affect the specific heat capacity of a
solution
Hypothesis: Increase in concentration of salt solution will increase the specific heat capacity of a liquid
Variables: Manipulating: concentration of solution
Responding: specific heat capacity
Control: volume of water
Apparatus: salt, water, beaker, metal, thermometer, stop watch, balance.
Diagram:
Procedures: (1) Pour 40cm3 of water in a beaker and record its temperature
(2) Add 10g of sodium chloride (Nacl) to the water and record new temperature
(3) Place the beaker over a heat source then record the time taken for boiling point
(4) Repeat the process using various mass of salt (Nacl) 20g and 30g respectively
(5) Record your results
Expected Results:
Mass of Salt
10g
20g
30g
Temperature (00C)
1100C
1200C
1500C
Precautions: (1) Ensure that the mass of the salt is accurate
(2) Ensure that the same amount of water is poured in the beaker
Sources of error: (1) Parallax error in reading the temperature may occur
(2) The incorrect amount may have been placed in the beaker
Experiment #9
Title: Center of Gravity
Aim: To locate the center of gravity of an irregular shape lamina
Apparatus: Material: clamped stand, needle/nail, lamina, string, stone.
Diagram:
Procedures: 1. The equipment was obtained and the experiment was set
2. It was ensured that the pivot (nail/optical, pin stuck in cork was stable by placing it in a
stand or on the bench top)
3. A hole was placed close to the body and suspended on the pivot to ensure that it was
spinning freely.
4. The plumLine was suspended on the pivot and when the lamina was in equilibrium the
position of the plumLine was recorded at X. The X was placed as close as possible to the edge; a
sharp pencil was used to mark the position of the plumLine. The steps were repeated for
another position.
Discussion: The center of gravity is the point through which the total weight of the body is considered to
act
Sources of error: (1) The diagram was affected by parallax
(2) Lamina was not hang freely
Conclusion: The position of the center of gravity was found and the aim was found.
Experiment #10
Title: Pressure
Aim: To investigate fluid pressure and depth
Apparatus: Two 1 litre plastic bottle, nail water, tape, meter ruler.
Diagram:
Procedures: 1. A nail was used to punch three holes in the containers as shown in the diagram above
2. The containers were placed at the edge of the table and another container placed below
to catch the water
3. The holes in the containers were taped. Water was poured in the containers until it
passed the holes. The tape was removed and the flow of water from each hole of the
container was observed
4. The water flow from each hole of the container was measured
5. The equipment was repeated with the containers covered
Data Collected:
TABLE SHOWING RESULTS OF CONTAINER 1 IN PRESSURE EXPERIMENT
A
B
C
Uncovered Container (cm)
3
6
8
covered Container (cm)
0
3
5
TABLE SHOWING RESULTS OF CONTAINER 2 IN PRESSURE EXPERIMENT
A
B
C
Uncovered Container (cm)
5
5
5
covered Container (cm)
4
4
4
Data Analysis: The pressure varied in container 1. In container 1 the pressure was highest at hole ‘C’ and
lowest at hole ‘A’.
Conclusion: From the experiment it was concluded that as depth increases pressure also increases