Two substances are identical except that the electron mean free time for substance A is twice the electron mean free time for substance B. If the same electric field exists in both substances the electron drift speed in A is:

Complete Question  

Two substances are identical except that the electron mean free time for substance A is twice the electron mean free time for substance B. If the same electric field exists in both substances the electron drift speed in A is:

Select one:

a. half that in B

b. four times that in B

c. twice that in B

d. the same as in B

e. one fourth that in B

Option c is correct

Explanation:

From the question given

The electron mean free time substance for substance is

The electron mean free time substance for substance B is

Generally the drift velocity for substance A is mathematically represented as

Generally the drift velocity for substance B is mathematically represented as

So

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