A dynamo primarily converts

• A. Mechanical energy into electrical energy
• B. Electrical energy into kinetic energy
• C. Potential energy into kinetic energy
• D. Kinetic energy into potential energy

Which of the following factors does not affect the electric resistance of wire?

• A. length
• B. mass
• C. temperature
• D. cross-sectional area

The fiqure below represents a block-and-tackle pulley system on which an effort of W Newtons supports a load of 120.0N. If the efficiency of the machine is 40, then the value of W is

• A. 28.0N
• B. 48.0N
• C. 288.0N
• D. 50.0N

A mass of a liquid at 30^oC is mixed with a mass of the same liquid at 70^oC and the temperature of the mixture is 45^oC. Find the ratio of the mass of the cold liquid to the mass of the other liquid.

• A. 3 : 5
• B. 5 : 3
• C. 3 : 7
• D. 7 : 3

Heat transfer by conduction is similar to wave motion because

• A. there is increase in temperature
• B. transfer of materials is involved
• C. charged particles vibrates at right angles
• D. no transfer of materials is involved

Which of the units of the following physical quantities are derived?

I. Area

II. Thrust

III. Pressure

IV. Mass

• A. I, II, III and IV
• B. I, II, and III only
• C. I, II, and IV only
• D. I and IV only

A supply of 400V is connected across capacitors of 3μf and 6μf in series. Calculate the charge

• A. 8 x 10⁻⁴C
• B. 4 x 10⁻²C
• C. 8 x 10⁻³C
• D. 4 x 10⁻⁸C

(a) List two types of waves, apart from light, that can be plane polarised

(b) State two applications of plane polarised light.

Which of the following statements is not correct?

• A. A sea breeze is due to convection in air
• B. Cotton materials are better than woollen ones for use in hot weather
• C. Convectional currents play an important role in the cooling of the engine of a motor car
• D. The vacuum space in a flask helps to reduce heat loss by radiation.

Which of the following have the longest wavelengths?

• A. Infra-red rays
• B. Gamma rays
• C. X-rays
• D. Radio waves