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3 marksElectronics

CSEC Physics · 1992 · Paper 2 · Question 4(a)(iii)

Operation of a d.c. dynamo, electromagnetic induction, and transformers.

The coil makes 10 revolutions in one second. On the axes provided, sketch a graph to represent the variation of output current with time during the first two revolutions of the coil. Indicate the scale used on EACH axis.

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Other parts of this question

  1. 4(a)(i)Write in the name of the components labelled A, B, C and D on the dotted lines provided.[4 marks]
  2. 4(a)(ii)The terminals X and Y are connected to a 2 Ω resistor. The peak value of the potential difference is 4 V. Calculate the peak value of the output current.[1 mark]
  3. 4(a)(iv)If the number of turns of wire on the coil is increased, with no other change, state the effect, if any, on the frequency of the output current.[1 mark]
  4. 4(a)(v)If the number of turns of wire on the coil is increased, with no other change, state the effect, if any, on the peak value of the output current.[1 mark]
  5. 4(a)(vi)If instead of increasing the number of turns of wire, the speed of rotation of the coil is increased with no other change, state the effect, if any, on the…[1 mark]
  6. 4(a)(vii)If instead of increasing the number of turns of wire, the speed of rotation of the coil is increased with no other change, state the effect, if any, on the…[1 mark]
  7. 4(b)A mechanic states that a transformer cannot be used with the d.c. dynamo to obtain a higher potential difference as transformers work only with alternating…[4 marks]

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