A 40-W instrument has a resistance of 90Ω. On what voltage should it be operated normally?

• A. 60V
• B. 150V
• C. 225V
• D. 3600V

Which of the following statements is an effect of compressing gas molecules at constant temperature?

• A. The pressure on the molecules decreases.
• B. The molecules gain more kinetic energy.
• C. The molecules make more impact per second on the walls of the container.
• D. The molecules increase in size

The primary aim in high tension transmission is to

• A. minimize electrical energy losses due to heat production
• B. increase the rate of energy transfer by using high voltage
• C. increase the current in the wire
• D. generate electricity at high current and low voltage

a) Define heat capacity and state its unit.

(b) List two effects of heat on a substance.

(c) Explain how a tightly fitted glass stopper could be removed from a reagent bottle.

(d) A quantity of pepper soup of mass 800 g poured into a plastic container with a tight-fitting lid has a temperature of 30°C. The container is then placed in a microwave oven, rated 1200 W and operated for 3 minutes.

(i) Calculate the final temperature attained by the soup. (Assuming no heat losses).

(ii) Explain why containers with tight-fitting lids are not suitable for use in microwave cooking.

(iii) When the soup is brought out and allowed to cool, a dent is observed on the container. Explain. [Take specific heat capacity of the soup = 4000 Jkg\(^{-1}\) K\(^{-1}\)]

A stone of mass 300g is released from rest from the top of a bulding of height 100m. Determine the kinetic energy gained by the stone when it is a quarter way down from the point of release.[g = 10 ms^-2]

• A. 750.0J
• B. 225.0J
• C. 75.0J
• D. 22.5J

The angle which the direction of the earth magnetic field makes with the horizontal at a palace is know as.

• A. angle of contact
• B. angle of dip
• C. angle of declination
• D. magnetic meridian

Fleming's right hand rule is also called the

• A. motor rule
• B. dynamo rule
• C. screw rule
• D. thumb rule

Which of the following statements describes a body in a stable equilibrium correctly?

• A. a person walking on a tight-rope
• B. ball on a smooth horizontal table
• C. ball resting on an inverted hemisphere bowl
• D. ball in the middle of a nemispherical bowl

A magnet relay is a device used for?

• A. reading the magnitude of magnetic flux
• B. controlling another circuit carrying larger current
• C. turning in sports
• D. storing magnetic field

A body starts from rest and accelerates uniformly at 5ms^-2 until it attains a velocity of 25ms^{-1. Calculate the time taken to attain this velocity}

• A. 2.5s
• B. 5.0s
• C. 10.0s
• D. 125.0s