PHYSICS | NECTA 2017 | Question 11

(a)(i) How does the increase of length and cross-section area of a conductor affect its resistance?

(b)(i) State the function of a circuit breaker in a wiring system.

(ii) Determine the ratio of resistance of wire A to that of wire B which are made up of the same material such that wire A has half the length and twice the diameter of wire B.

(c) An electric kettle contains 720 W heating units:

(i) What current does it take from 240 V mains?

(ii) How long will the kettle take to raise the temperature of 2 kg of water at 30°C to its boiling point?

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