Physics Paper 2 Marking Scheme
KCSE CLUSTER TEST 14
Physics Paper 2
SECTION A (25 Marks)
Answer all the questions in this section in the spaces provided2 marks
P acquires Negative charges while Q positive charges. -Negatively charged rod repels negative charges on Q leaving it positively charged. The repelled charges move to P making it negatively charged.
2 marks
2 marks
The razor on wooden block is attracted and one on the soft iron block is not. The soft iron is magnetized through induction
3 marks
1 marks
3 marks
– End X is shallower
1 marks
2 marks
Brightness of the bulb reduces as water continues to be heated;
Resistance of copper wire increases with increase in temperature
2 marks
–Has high melting point
1 marks
2 marks
Microwave – infrared –visible light- X rays
1 marks
To reduce energy loss through formation of eddy currents.
1 marks
3 marks
SECTION B (55 Marks)
Answer ALL the questions in this section in the spaces provided.Place the lens a distance u, from the object, move the screen to and from till a sharp image is formed on the screen. Measure the distance v between the screen and lens.
Collect several set of distance u and v. Use the formula to calculate f for each set
and find the average value of f.
b)
14 marks
12 marks
(a) Lower current, hence minimize power loses.
(b) The fuse and switch are on neural instead of live wire.
(c) -Strength of magnet Any point 1mark -Movement speed of coil.
(d)i) A -Primary coil B - Cell (source of current).
ii) -On contact there is high induced e.m.f across primary coil. -this is stepped up by the secondary coil C.
-This means high voltage at the sharp terminals thus sparks to burn fuel.
-Direction of induced e.m.f is such as to oppose the change causing it
11 marks
. (a) Hand x- ray have high penetrating power and high frequency, soft x-ray have low frequency and low penetrating power.
(b)i) P ……………….anode ; R………………..cathode;
ii) Q-made of lead ; -Lead cannot be penetrated by stray x-ray;
iii) Increase the voltage of heater circuit. (LT); (c)i) Y gain = 10VICM Reading = 2 cm
9 marks
(b) I Alcohol condenses around the ions formed by the radiation to form the narrow tracks.
II Cools the bottom of the chamber and also condenses alcohol below its normal temperature.
III Solid CO2 cools the bottom of the chamber, alcohol vaporizes and spreads throughout the chamber.
It is cooled below its normal temperature in case of a radiation, air around the path of the radiation is ionized.
Alcohol condenses around these ions to form a narrow cloud.
13 marks