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Thursday, 28 November 2013

Q.No.13.1: - A potential difference is applied across the ends of a copper wire. What is the effect on the drift velocity of free electrons by (i) Increasing the potential difference. (ii) Decreasing the length and the temperature of the wire.

Q.No.13.1: - A potential difference is applied across the ends of a copper wire. What is the effect on the drift velocity of free electrons by
(i)    Increasing the potential difference.
(ii)   Decreasing the length and the temperature of the wire.
Ans: - (i) It is obvious that drift velocity of free electrons in the copper wire will increase do to increasing potential difference.

(ii) If the drift velocity of free electrons is increasing then it means that resistance in the conductor is low at that time and when we decrease the length of the conductor then basically we are trying to decrease the number of atoms and decreasing resistance. As a result the drift velocity of free electrons increases. We know that resistance depends upon temperature change and if we decrease temperature of wire then it mean we are decreasing resistance and as a result increasing drift velocity. So, we can say that by increasing potential difference, decreasing length and temperature of conductor we are increasing drift velocity of electrons.

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