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Question : 9
Total: 29
Write a relation between current and drift velocity of electrons in a conductor. Use this relation to explain how the resistance of a conductor changes with the rise in temperature.
Solution:
The relation between current and drift velocity of electron is
I = n e A v d
n = number density of electrons
A = cross-sectional area
e = charge of electron
I = current
v d =
Ï„
E = potential difference across the conductor
Ï„ = Relaxation time
l = length of the conductor
∴ I = n e A ×
Ï„
R =
=
As the temperature increases, the number of collisions increases andτ
As the temperature increases, the number of collisions increases and
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