In the fig below, XY is of length 1m, The value of R at balance point Z is

• A. 3.0Ω
• B. 13.3Ω
• C. 15.0Ω
• D. 30.0Ω

A man and his friend have masses 70kg and 60kg respectively. If they are seated 1.0m apart, calculate the gravitational force of attraction between them. (G = 6.67 x 10^-11 Nm² kg^-2)

• A. 1.59 x 10^-14 N
• B. 2.80 x 10^-7 N
• C. 1.30 x 10^-2 N
• D. 6.30 x 10¹³ N

Two solids P and Q of equal mass are heated to the same temperature and dropped simultaneously into two identical containers X and Y containing equal volumes of water at room temperature. The temperature of X will rise higher than that of Y only if the

• A. volume of P is greater than that of Q
• B. specific heat capacity of P is higher than that of Q
• C. density of P is greater than that of Q
• D. density of P is lower than that of Q

(a) (i) Explain latent heat.

(ii) State two factors that affect the rate of evaporation of a liquid

(b) Explain each of the following observations:

(i) On a dry day, water in a clay pot is cooler than water in a closed plastic container;

(ii) Food gets cooked faster in a pressure cooker than in an ordinary cooking pot.

(c) State two effects of heat on a substance.

(d) A 40 V electric heater is used to supply a current of 12 A for 1400 s to a body of mass 1.5 kg at the melting point of the body. The body melts and its temperature rises through 60\(^o\)C in an extra 72 s. Determine the:

(i) latent heat of fusion of the body;

(ii)specific heat capacity of the body.

A rectangular coil can rotate in a magnetic field. The two ends of the coil are soldered respectively to the two halves of a commutator. Two carbon brushes are made to press lightly against the commutator and when these are connected in a circuit with a battery and a rheostat, the coil rotates. This is a description of

• A. a moving coil ammeter
• B. a D.C generator
• C. a D.C electric motor
• D. An induction coil

Determine the potential difference. V across the parallel resistors

• A. 2.0V
• B. 2.3V
• C. 3.0V
• D. 0.7V

The two person of a body undergoing a uniformly accelerated motion are (10s, 10ms^-1) and (30s, 50ms^-1). On the velocity-time graph pf the body.

• A. 0.5ms^-2
• B. 2.0ms^-2
• C. 10.0ms^-2
• D. 40.0ms^-2

An astronomical telescope has objectives and eye-piece lenses of focal length 3.5m and 5cm respectively. Determine the magnifying power of the telescope when in normal adjustment

• A. 70.0
• B. 17.5
• C. 7.0
• D. 0.7

In a controlled thermal fission reactor, the use of control rods will not affect the

• A. energy generated in the nuclear reactor
• B. rate of production of the neutrons.
• C. speed of the neutrons released on fission.
• D. amount of radiation produced in the nuclear reactor

The pin-hole camera produces a less sharply defined image when the

• A. pin-hole is larger
• B. illumination is less
• C. screen is further from the pin-hole
• D. object is further from the pin-hole