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1 markElectrical Quantities

CSEC Physics · 1990 · Paper 2 · Question 5(b)(ii)

A 5.0 Ω resistor has a maximum power rating of 5.0 W and is connected to a d.c. power supply.

The resistor is connected to an a.c. supply and an alternating current flows with a peak value equal to the maximum permissible current. Explain why the rate of energy conversion using a.c. will be less than that using d.c.

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Other parts of this question

  1. 5(a)(i)State the essential difference between direct current and alternating current.[2 marks]
  2. 5(a)(ii)A split-ring commutator is connected to the a.c. generator. On the axes provided, draw a graph to represent the output current assuming no other change in the…[3 marks]
  3. 5(a)(iii)The commutator is removed and a p-n diode is placed in series with the a.c. generator. Distinguish between the p-type material and n-type material of which the…[4 marks]
  4. 5(a)(iv)On the axes provided, draw a graph of current against time to represent the output of the a.c. generator and diode.[3 marks]
  5. 5(b)(i)Calculate the maximum permissible current in the resistor.[3 marks]

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