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Question
The potential difference applied across a given conductor is doubled. How will this affect (i) the mobility of electrons and (ii) the current density in the conductor? Justify your answers.
Solution
Mobility of electron `mu = (v_d)/E = (v_dl)/V`
as `E = V/l`
Hence, `mu prop 1/V`
If V becomes 2V, the mobility will become half. The current density is given by
`J = n ev_d`
J = `n e.(eVtau)/(ml)`
J = `(n e^2Vtau)/(ml)`
J ∝ V
When V become 2V current density will become twice.
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