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2 marksThe p-n Junction Diode

CAPE Physics Unit 2 · 2016 · Paper 2 · Question 4(c)(iii)

A cylindrical copper wire carries a current of 6 A, with radius 6.9 \times 10^{-4}\text{ m} and free electron density 6.5 \times 10^{28}\text{ m}^{-3}.

Would the drift velocity in a semiconductor material of similar dimensions carrying the same current be greater than that of the conductor in (c)(i)? State a reason for your answer.

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Other parts of this question

  1. 4(a)Explain the term 'drift velocity' when applied to the movement of electrons in a conductor.[2 marks]
  2. 4(b)Write the meaning of EACH variable in the equation I = nevA and state the unit in EACH case.[4 marks]
  3. 4(c)(i)Calculate the drift velocity of electrons in the wire in millimetres per second.[5 marks]
  4. 4(c)(ii)Suggest a reason why this value is so small compared to the other values of electron velocity commonly encountered in physics.[2 marks]

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