KAKAMEGA CENTRAL DISTRICT PHYSICS PRACTICAL QUESTIONS AND ANSWERS

KAKAMEGA CENTRAL DISTRICT PHYSICS PRACTICAL QUESTIONS

Question 1

You are provided with the following apparatus;

• A wooden plank of length 1m or a meter rule
  
• A meter rule
  
• A half- meter (can be shared)
  
• Two complete retort stands
  
• Some thread
  
• A stop watch/ clock
  

 Proceed as follows:-

1  a) Set up the apparatus as shown. Ensure the loops on the wooden plank and meter rule are

  loose to enable easy sliding of the threads.

  The separation between the meter rule and the plank must remain 20cm throughout

the experiment.  

b)  i) Adjust the positions of the thread such that one is at the 10cm mark and the other at the 90cm

mark so that the distance marked d is 80cm. Maintain the threads vertical
by moving the

loops on the plank.

 ii) Now displace one end of the meter rule slightly on a horizontal plane so that when released

it oscillates about a vertical axis as in the figure below.

 iii) Measure the timer for 10 oscillations and record the value in the table provided below

c)  i) Repeat the procedure in (b) above for the values of d shown in the table (set the values of

d by adjusting the positions of the loops in steps of 5cm on both sides)

 ii) Complete the table

 d)  i) On the grid provided, plot a graph of T² (y – axis) against 1/d² (M-²) ii) Determine the slope of your graph  

  iii) Given that T² = 16K²
where K is a constant. Use the graph to determine the value of K

5d²

QUESTION 2

 This question has two parts A and B. Answer both parts.

 You are provided with the following:

• A lens and a lens holder
  
• A candle
  
• Object consisting of a hole 2cm in diameter and parallel wires 1.5cm apart in a stiff card. (See diagram below)
  
• A screen
  
• A meter rule  

Proceed as follows:-

 a) Illuminate the object with the candle flame.

 b) Arrange the object, lens and screen in line as shown in figure 3 below  

c) Measure the distance, d, between the two parallel wire that acts as the object

d = ………………… cm

d) Adjust the lens, u to 80cm

e) Move the screen until a clear image is formed on it.

f) Measure the distance, X, of the image, making sure that what you measure is an image corresponding

to the previous reading, d.

Record these values in the table below:-

g) Repeat your readings of x with u = 70, 60, 50, 40 and 30cm and complete the table

h)  i) On the grid provided plot a graph of u (y – axis) against d/x  

 ii)  I . Determine the slope, S of the graph

II. Find the intercept on the u – axis  

PART B

 You are provided with the following:-

• A jockey J  
  
• An ammeter  
  
• A voltmeter  
  
• A switch
  
• 6 connecting wires, Z with crocodile clips on one end
  
• A resistor wire labeled XY mounted on a piece of wood having a millimeter scale  
  
• 2 new dry cells  
  

 Proceed as follow:

I)  i) Connect the circuit as shown below:

ii) Close the switch and note the voltmeter and ammeter readings when XJ = 10cm

iii) Repeat procedure (i) and (ii) above with XJ = 20 cm and enter in the table 3 as below: *KKC*

Table 3:-

J) Given that log I = n log V + log k, where k and n are constants, determine the values of k and n

KAKAMEGA CENTRAL DISTRICT PHYSICS PRACTICAL ANSWERS

1. c)i) Repeat the procedure in (b) above for the values of d shown in the table (set the values of d by

adjusting the positions of the loops in steps of 5cm on both sides)

 ii) Complete the table

 d ) i) On the grid provided, plot a graph of T² (y – axis) against 1/d² (M-²)

  ii) Determine the slope of your graph  

Slope = (250 -0) X 10
^-2 S²  S = 2.5 X 10 ^-1 M² S²

(100 -0) X 10 ^-1 M ^-2 S= 0.25 M²S²

iii) Given that T² = 16K² where K is a constant. Use the graph to determine the value of

5d²

16K² = slope   K =
0.25 X 5 M²S²

5 16

K² = S X5   K = 0.2795

16

QUESTION 2    

c) Measure the distance, d, between the two parallel wire that acts as the object  d =1.50 cm

Record this value in the table below.

g) Repeat your readings of x with u = 70, 60, 50, 40 and 30cm and complete the table  (5 marks)

i) On the grid provided plot a graph of u (y – axis) against d/x

ii)  I . Determine the slope, S of the graph

S = 85 -40   S = 45  

275 -80 X 10^-2   195 X10^-2

 = 23.076 cm

II. Find the intercept on the u – axis  

U – intercept = 20.0 cm

PART B

iii) Repeat procedure (i) and (ii) above with XJ = 20 cm and enter in the table 3as below

Table 3

J) Given that log I = n log V + log K, where k and n are constants, determine the values of k and n

log(0.45) = n log (1.1) + logk -0.03468 = 0.0414n

log(0.25) = n log (1.5) + logk -0.6021 = 0.1761n

0.2553 = -0.13469n

n= 1.8955

T. 6532 0.414 n = 0.2553

– T.3979 = 0.1761 n -0.1347

0.2553 T.8653 n = -1.8955

log(0.45) = -1.8955 log(1.1) + log k

log k = log (0.45) + 1.8955 log (1.1)

= T .6532 + 1.8955X0.0414

= T.6532

+ 0.0785 log = T.7317

T .7317

 K = 0.53913.