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The conductivity of a semiconductor incr...

The conductivity of a semiconductor increases with increase in temperature because

A

number density of free current increase

B

relaxation time inceases

C

both number density of carries and relaxation time incease

D

number density of carries increases relaxation time decreases but effect of decrease in relaxation time is much less than increase in number density

Text Solution

Verified by Experts

The correct Answer is:
d
The conductivity of a semiconductor increases with increases in temperature because the number density of current carries increases , relaxation time decreases but effect of decrease in relaxation in much less than increase in number density .
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Why does the electrical conductivity of semiconductors increase with rise in temperature ?

Statement I : Electrical conductivity of semiconductors increases with rise in temperature. Statement II : There is a small energy gap between conduction band and valence band.

Knowledge Check

  • Assertion (A) : The electrical conductivity of a semiconductor increases with increase in temperature. Reason (R ) : With increase in temperature, large number of electrons from the valence band can jump to the conduction band.

    A
    If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`
    B
    If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`
    C
    If `(A)` is correct, but `(R)` is incorrect.
    D
    If both `(A)` is incorrect, but `(R)` is correct.

  • Statement 1: Conductivity of semiconductor increases with increase in temperature. Statement 2: Forbidden energy gap is highest for semiconductors.

    A
    Both Statement-1 and Statement-2 are true, and Statement-2 is the correct explanation of Statement-1.
    B
    Both Statement-1 and Statement-2 are true but Statement-2 is not the correct explanation of Statement -1.
    C
    Statement-1 is true but Statement-2 is false.
    D
    Statement-1 is false but Statement-2 is true.

  • Statement 1: Conductivity of semiconductors decreases with increase in temperature Statement-2: More electron goes from valance band to conduction band with increase in temperature.

    A
    Both Statement-1 and Statement-2 are true, and Statement-2 is the correct explanation of Statement-1.
    B
    Both Statement-1 and Statement-2 are true but Statement-2 is not the correct explanation of Statement-1.
    C
    Statement-1 is true but Statement-2 is false.
    D
    Statement-1 is false but Statement-2 is true.

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    Read the following statements carefully : Y : The resistivity of a semiconductor decreases with increase of temperature. Z : In a conducing solid, the rate of collisions between free electrons and ions increase with increase of temperature. Select the correct statement (s) from the followin :

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