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SOTIK DISTRICT 1ST EXAM PHYSICS PRACTICAL QUESTIONS
1. You are provided with the following apparatus:-
- Full retort stand
- Optical pin
- 20cm copper wire
- Protractor
- Two pieces of plasticine
- Cork
- Stop watch *
A. Bend a wire in the middle. Place it on a protractor and adjust an angle of 50o. Attach the
two pieces of plasticine on the ends of the wire. Then place the wire on the optical pin as shown
B. Displace the wire horizontally by a small angle and set it in oscillation. By use of stop watch
obtain time for 20 oscillations. Repeat this procedure for values of , 60o, 70o, 80o, 90o and
100o. Record your measurements in the table and complete it determining values of period T,
frequency (Hz), 2 (Hz)2 and cos (/2)
Angle o | Time t for 20 oscillations in sec | Period T (Sec) | Frequency (Hz) | 2 (Hz)2 | cos(/2) |
50 | |||||
60 | |||||
70 | |||||
80 | |||||
90 | |||||
100 |
C. (i) Draw graph of 2 (Hz)2 against cos(/2)
C. (ii) Determine the gradient of the graph
C (iii) The relationship betweenand is 4L2 =150Z cos(/2) – 10. Where L is 0.2m.
Determine the constant Z by the graph
Question 2
PART A
You are provided with;
– 1000ml measuring cylinder , Clean water, Two optical pins, Retort stand, Cork, and a Wooden block
A. Place optical pin in the measuring cylinder. Add water to reach 400cm3 mark. View the optical pin
through water and locate its image.
B. (i) Place another optical pin in cork and then in retort stand clap as shown. Move this optical pin
(search pin) up and down until it coincides with image optical pin as seen through water. Read off
the volume reading of the search optical pin when it coincides with image of object optical pin.
Repeat this procedure for water volume marks of 600, 700,800, 900, and 1000cm3. Enter your
observations in table *
Table
B (ii) Draw a graph of H(cm3 ) against h(cm3)
C (i) Determine slope of your graph
(ii) Determine M if H = mh + C where M and C are constants
(iii) If m
=
M where M is refractive index of water, determine M
M-1
Part B
You are provided with a lens, plane mirror, retort stand, cork and optical pin and half metre rule.
Set up apparatus as shown
Move the object optical pin up and down. Look for its image. When object optical pin coincides with its image measure the vertical distance from mirror to object optical pin. Repeat the experiment.
(i) 1st attempt: Vertical height of optical pin = __________cm
2nd attempt: Vertical height of optical thumb pin =______________________cm
(ii) Determine the average vertical height of optical thumb pin
(iii) Now determine the focal length of the lens using the above measurements
SOTIK DISTRICT 1ST EXAM PHYSICS PRACTICAL ANSWERS
Question 1
Angle o | 50 | 60 | 70 | 80 | 90 | 100 | |
Time t sec for 20 oscillations | 11 | 12 | 13 | 14 | 16 | 18 | T sec, 1mk for each correct value max 5mks |
Period T= t/20 sec | 0.55 | 0.60 | 0.65 | 0.7 | 0.8 | 0.9 | 1mk for at least 4correct evaluations |
Frequency = I T | 1.82 | 1.67 | 1.58 | 1.43 | 1.25 | 1.11 | |
2 (H2)2 | 3.312 | 2.789 | 2.496 | 2.045 | 1.563 | 1.232 | 1mk for at least 4 correct evaluations |
cos() 2 | 0.906 | 0.867 | 0.819 | 0.766 | 0.707 | 0.642 | 1mk for at least 4 correct evaluations |
N/B
(i) – Period T = t sec should be correctly evaluated to 2 d.p
20
– Frequency should be correctly evaluated to 2 d.p
– 2 (H2)2 should be correctly evaluated to 3 d.p
– Cos(/2) should be correctly read to 3 d.p
C(i) Axes 1mk
Scale (1mk)
Simple and uniform
Plotting (2mks)
Plot with accuracy of small lines. Each correctly plotted point award ½mk up to max of (2mks)
Line (1mk)
+ve slope line with negative y-intersect
C (ii) Award gradient mark only when line is correct
Intervals (1mk)
Substitution 1mk
Evaluation 1mk
Gradient = 3.31 – 2.05 = 1.26 = 9
0.91 – 0.77 0.14
(iii) 4L2 = 150Z Cos /2 – 10
2 = 150Z Cos /2 – 10
4 L
Slope = 150Z
4L
= 150Z = 9
4L
Z = 4L X 9
150
= 4 22 x 0.2 x 9
7 150
= 0.1509
N/B:- Pick point from line substitute in equation and solve for Z
Question 2
B. (ii) Axes (1mk)
Scale (1mk)
Simple and uniform
Plotting (2mks)
Correctly plotted point (½mk) for max of 2mks
Line 1mk
Straight line with + ve gradient passing though at least 3 correctly plotted points
C. (i) Without getting mark for line award (0 marks) for slope
Intervals 1mk
Evaluation (1mk)
Accuracy 1mk
600-400 = 200 = 4 (no units)
150 – 100 50
(ii) M = slope = 4 (1mk)
(iii) 4 = M
M – 1
4M – 4 = M
3M = 4
M = 4
3
M= 1.33 (1mk)
N/B:- You can also pick two points on the time to solve for M by substituting in equation and solving
Simultaneously.