Figure shows a piece of semiconductor (pure one) `S` in series with a variable resistor `R` and a source of constant voltage `V. S` is heated and the current is kept constant by adjustment `R`. Which of the following factors will decrease during this process?

`(1)` The drift velocity of the conduction electrons in `S`.
`(2)` The `DC` resistance of `S`
`(3)` The number of conduction electrons in `S`. which of the following is correct?

Options

A. only `1`
B. `1` and `2`
C. `1,2` and `3`
D. only `3`

Answer

B

Explanation

Note that drift velocity in semiconductors in affected by an increases in temperature in the same way as in metals i.e., reduced due to an increases in the number of collisions with the lattice ions. Which vibrate with greater amplitude at a higher temperature?