## MIGORI/NYATIKE DISTRICT PHYSICS PRACTICAL QUESTIONS

Q.1  You are provided with the following apparatus:-

600 ml beaker.

– A measuring cylinder (100ml).

– Plasticine.

– A meter rule.

– Distilled water supplied in a 500 ml wash bottle.

– Candle.

– Screen.

– Tissue paper, 30 cm ruler

Proceed as follows:-

a i) Add 310 ml of water to the beaker and obtain h, the height in cm of the water above

the base of the beaker.

h = …………………………………. cm

ii) Calculate an approximate value of R, the internal radius in cm from the formula.

ecolebooks.com

R = 100

h

b) i) Fill the beaker with more water and set up the apparatus as shown in figure 1. The vessel

should be placed at around 50 cm mark on the scale.

ii) Starting with 1OR, adjust the screen until you see a sharp bright vertical line.

iii) Record the distance V of the image in table 1 whose image is sharpest. Repeat the

experiment with values of u between 1OR and 3R cm.

 u 3R 4R 5R 6R 7R 8R 9R 10R u (cm) v (cm)

c) Plot the graph of u against v.

d) From the graph determine.

i) v1 the value of v for which v = u.

ii) u1 the value of u for which u = 2v.

e) Calculate f, the effective focal length of the ‘lens’ from the formula.

f = u1 + u1

5

f) Give the approximate value of R/f
.

Q2.  Part A.

You are provided with the following apparatus:-

• Boiling tube.
• A cork with a hole and a thermometer to fit in it.
• Complete retort stand.
• Source of heat.
• Some distilled water in a beaker.
• Stop-watch.
• Tissue paper.
• 250ml beaker.

Proceed as follows:-

a) Heat the water in a beaker until it boils. It is essential that the water is kept boiling throughout

the experiment.

b) Clamp the boiling tube as shown in figure 2 making sure that the tube does not touch the

base of the retort stand.

figure 3 figure 2

c) Using a 250 ml beaker, transfer some boiling water into the boiling tube making sure that

some space is left. Plug the tube with the cork that carries the thermometer as shown in

figure 3.

d) Starting with the temperature of 80oC, note the temperature of the water every 1
minute

i) Tabulate your results in a table as shown below:-

 Time t (min) 0 1 2 3 4 5 6 7 8 9 10 Temperature (oC)

ii) Plot a graph of temperature  (oC), against t, min.

iii)Find the gradient d of your graph at the temperature of 70oC

dt

. iv) Find the rate of heat loss, R, at the temperature of 70oC given that

R = K d where K = 1.23 x 104

dt

Q.2  Part B

You are provided with the following:-

• Two New identical dry cells (size D)
• Nichrome wire labelled AB, mounted on a metre rule.
• An ammeter (0 – 1.5A) or (0 – 2.5A).
• A voltmeter 0 – 5V.
• A cell holder.
• 8 connecting wires at least 4 with crocodile clips.
• Jockey.
• A switch

Proceed as follows:-

a) Connect the circuit as shown in figure 4 below

b) Connect the end A and B where AB = 100 cm across the terminals as shown in figure 4.

Close the switch and measure both I and p.d., v across the wire AB.

i) Current I = ……………………………………………………………A

ii) p.d. V = ………………………………………………………………V

iii) Measure the e.m.f. of the cells, E = ……………………………….. V

iv) Given that equation E = V + Ir, determine the internal resistance of the two cells.

## MIGORI/NYATIKE DISTRICT PHYSICS PRACTICAL ANSWERS

1.  (a) (i) h = 5.0cm

(ii) R= 100

h

= 100

5

= 4.47cm

(b) (iv)

 U 3R 4R 5R 6R 7R 8R 9R 10R U(cm) 13.40 17.90 22.40 26.80 31.30 35.80 40.2 44.70 V(cm) 21.0 15.0 14.0 12.5 12.0 11.5 11.0 10.5

Consistency in values

(c) graph plotting

3 and 4 points

5-8 points

scale

curve

axis

(d) (i) V1 = 17.5cm

(ii) U1 = 2.26.25

Give reading off from the graph *UGU* each

(e) f = U1 + V1

5

= 17.5 + 27.5

5

= 45 = 9cm

5

(f) R = 4.47

f 9

= 0.496667

= 0.50

(total 20mks)

2.  Part A

(d)

 Time t (min) 0 1 2 3 4 5 6 7 8 Temperature (oC) 80 77 74 71 68.5 66.5 64 62 60.5

(i) trend

decimal place acquired

filling the table

(ii) Plotting  P2

scale  S

Axis  A

curve  C

(iii) Tangent line drawn at 70oC and identifying two points

(5,66 and (1,45, 74)

d = 74- 66

dt 1.45 – 5

= 8

-3.15

= -2.540

(iv) Heat loss, R = K d

dt

= 1.23 x 104 x 2.540 = 31,242J

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