A 12Ω resistor dissipates 8kJ of heat in 20s. Calculate the current through the resistor

• A. 5.8A
• B. 6.9A
• C. 30.0A
• D. 33.3A

State three methods of polarizing an unpolarized light

The terminals of a battery of emf 24.0 V and internal resistance of 1.0Ω is connected to an external resistor 5.0Ω. Find the terminal p.d.

• A. 18.0V
• B. 12.0V
• C. 16.0V
• D. 20.0V

Which of the following is a scalar quantity?

• A. Momentum
• B. Acceleration
• C. Displacement
• D. Distance

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

• A. a suspended- coil vanometer
• B. a moving-cell ammeter
• C. a d.c generator
• D. an electric motor

A sound wave is produced fron a source ans an echo is heard t seconds afterwards. If d is the distance of the reflecting surface from the source, v the speed, p the wavelength and T the period of the wave, then

• A. d = \(\frac{2t}{\lambda}\)
• B. d = \(\frac{\lambda t}{2T}\)
• C. d = \(\frac{2T}{\lambda t}\)
• D. d = \(\frac{\lambda T}{2t}\)

(a) With the aid of a simple diagram, explain how a step down transformer works.

(b)(i) State three ways by which energy is lost in a transformer

(ii) Mention how each of the losses in (b)(i) above can be minimized

(c) A 95% efficient transformer is used to operate a lamp rated 60W, 220 V from a 4400 V a.c supply. Calculate the;

(i) ratio of the number of turns in the primary coil to the number of turns in the secondary coil of the transformer

(ii) current taken from the main circuit.

Two force each of 10N acts on a body, one towards the north and the other towards the east. The magnitude and the direction of the resultant force are

• A. 20N, 45°E
• B. 20N, 45°W
• C. 10√2N, 45°W
• D. 10√2N, 45°E

I.Chemical II.Sound III.Electricity

Which of the above forms of energy can directly be converted to light energy?

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

The instrument used to measure relative humidity is a

• A. Hygrometer
• B. Barometer
• C. Hydrometer
• D. Manometer