2 marksElectrical Quantities

CAPE Physics Unit 2 · May/June 2022 · Paper 2 · Question 2(c)(ii)

A small cylinder made of n-type semiconductor material has a diameter of 4 mm and a length of 1.0 cm. It carries the same rated current as the device in (a).

State how the electron drift velocity obtained in (c)(i) would compare with the electron drift velocity in a copper slug of identical dimensions carrying the same current. Explain your answer.

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Other parts of this question

2(a)Derive an expression for the current waveform, in the form I = I_p sin(ωt), when the device is operating at its rated current.[4 marks]
2(b)Sketch a graph of ONE cycle of the current waveform in (a), with axes labelled to show the values of the period and amplitude.[7 marks]
2(c)(i)Determine the MAXIMUM drift velocity of the charge carriers in the semiconducting cylinder if the number density of electrons is 3 × 10^17 cm^-3.[7 marks]
2(c)(iii)The resistance of the semiconductor cylinder in (c) was measured and found to be 80 Ω. Calculate the resistivity of the semiconductor in ohmmeters.[4 marks]
2(d)Sketch and label BEFORE and AFTER diagrams to describe the formation of the depletion layer in an unbiased p-n junction.[6 marks]

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