K.C.S.E Physics Q & A - MODEL 1999PP2QN05

K.C.S.E Physics Q & A - MODEL 1999PP2QN05

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a) A circuit consists of a battery, a metal wire, an ammeter and a switch connected in series. The switch is closed and the ammeter reading noted. The metal wire is now heated. State the observations made on the ammeter reading and give a reason for your answer.
b) An electric heater is made of a wire of resistance 100ohms and connected to a 240V mains supply. Determine the:
i) Power rating of the heater ii) Current flowing in the circuit.
iii) Time taken for the heater to raise the temperature of 200g of water from 23°C to 95°C.

(Specific heat capacity of water is 4200^-1K^-1)

iv) Cost of using the heater for two hours a day for 30 days.(The power and lighting company charges Kshs 5.00 per kilowatt — hour)

answers