UGENYA/UGUNJA DISTRICT PHYSICS PRACTICAL QUESTIONS AND ANSWERS

UGENYA/UGUNJA DISTRICT PHYSICS PRACTICAL QUESTIONS

Question 1

Part 1

1. You are provided with the following apparatus:-

• Clamp, boss and stand
  
• Optical pin fixed on a piece of cork
  
• Wire (length 30cm)
  
• Stop watch
  

Proceed as follows:

1. Bend the wire in the middle so that the angle formed is 20^o.
2. Set up the apparatus as shown in figure 1 below

1. (i) Displace the wire horizontally and allow it to swing freely. Record time t for 10 complete

oscillations.

(ii) Calculate the number of oscillations per second (f) f = ¹⁰/_t

1. Repeat the procedure above for the other given angles on table 1

(e) On the grid provided plot a graph of ²
against cos ^/₂

(f) Find the gradient of the graph, stating its units

Part II

You are provided with the following:-

• A rectangular glass block
  
• 1white plain sheet of paper
  
• 4 optical pins
  
• 4 thumb tacks
  
• A soft board
  

You are required to determine the refractive index of the glass block

Proceed as follows:

1. Fix the sheet of paper provided on the soft board using the thumb tacks
2. Place the rectangular glass block on the plain paper and trace its outline
3. Remove the block and draw a normal line at point O. Draw a line incident at an angle of 15^o as

   shown in figure 2 below

4. Stick 2 Pins P₁ and P₂ along the ray in and by looking through the glass block from the opposite

   side, stick two other pins P₃ and P₄ in line with the images of P₁ and P₂. Remove the glass block

5. With O as the centre, draw a circle of radius 5cm, to cut both the ray incident and the

   refracted ray at L and M respectively.

6. Using a set square, draw the perpendicular LN and MN to the normal
   1. Repeat the procedure (iii) to (iv) for other values of 30^o and 45^o as shown in figure 2

(c) Make LN and MN and record your values in the table 2 below

(d) Average value of refractive index = ______________

Question 2

You are provided with the following apparatus:

• Bi convex lens
  
• Lens holder
  
• Screen S
  
• Candle
  
• Screen with cross wire X
  
• Meter rule
  
• Plasticine
  

Proceed follows:-

1. Arrange the apparatus as shown in the diagram below:-‘

(Ensure the metre rule is firmly held on the bench by plasticine and the flame and

crosswire is at a horizontal level with the centre of the lens throughout the experiment)

(b) At a point a = 94cm from the screen X, obtain a sharp image of the crosswire on screen S by

adjusting the position of the lens along the metre rule. Record the values of b and c as shown in the

diagram.

(c) Adjust the position of screen S along the metre rule for a =90cm, obtain a sharp image of the

crosswire on screen S by adjusting the position of the lens. Record the corresponding values

of b and c

Repeat the procedure (a) and (b) above for other values of a = 94cm, 90cm, 86cm, 82cm,

78cm, 74cm and complete the table below

(d) Plot a graph of b(cm) (y-axis) against d

(e) Determine the slope S of the graph

(f) Given that the equation of the graph is determine the value of L from the

equation above

(g) What does L represent ?

PART II

Arrange the apparatus as shown below:

(a) Obtain a sharp image of flame on screen S by adjusting the position of screen S. Record the image

distance , V = _________cm

(b) Determine the constant m = V

u

(c) What does m represent?

UGENYA/UGUNJA PHYSICS PRACTICAL ANSWERS

1. (d )

1. Repeat the procedure above for the other given angles on table 1
   

(f) Gradient of y = (2.4475 – 1.75) Hz²

x (0.96 -0.68)

= 0.725 Hz²

0.28 = 2.589Hz²

(c) (i) f = 10 = 10

t 6.28

= 1.592Hz

PART B

(c)

(d) Average = 1.875 + 1.429 + 1.500

3

= 1.60 (2 dp)

Results of question 2

Trend 2 d=1

Correct = 3 4 correct = 2

total 06mks

(d) graph A ₂ S₁ P₃ L₁ = 7mks)

(e) Slope b = 2.5cm

d 1.3 S = 19.23cm

(f) L = 100

5

= 100

19.23 = 5.2Dioptres (5.0 ± 0.2)

(g) Power of the lens