# question number 34.

Mobility of charge μ, responsible of current is defined as the magnitude of drift velocity of charge per unit electric field applied i.e.

μ = v

_{d}/E

So, if electric field gets doubled the mobility reduced to half.

μ = v

_{d}/2E

Hence, mobility of the electrons depend on the applied electric field.

Now,

As temperature increases relaxation time decreases

we have ,$\mu =\frac{e\tau}{m}\left(e=charge,\tau =relaxationtime,m=mass\right)$$\mu =\frac{e\tau}{m}\left(e=charge,\tau =relaxationtime,m=mass\right)$

mobility is directly proportional to relaxation time. Relaxation time decreases hence mobility decreases.

Hence, mobility of the electrons also depend on the temperature.

Therefore, option c is correct.

Regards

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