## 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 ecolebooks.com 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 betweenand  is 4L2 =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

 Water level volume reading H cm3 Image level volume reading h cm3 400 600 700 800 900 1000

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 0.6 0.65 0.7 0.8 0.9 1mk for at least 4correct evaluations Frequency = I (H2) 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) 4L2 = 150Z Cos /2 – 10

2 = 150Z Cos /2 – 10

4 L

Slope = 150Z

4L

= 150Z = 9

4L

Z = 4L 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

 Water level volume reading Hcm3 Image level volume reading hcm3 4006007008009001000 100150175200225250

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.

subscriber

By

By

By

By