Consider the statements In a semi conductor (A) There are no free electrons at 0   K . (B) There are no…

Consider the statements
In a semi conductor
(A) There are no free electrons at 0 K.
(B) There are no free electrons at any temperature
(C) The number of free electrons increases with temperature,
(D) The number of free electrons is less than that in a conductor.
  1. B,C,D are true but A is false
  2. A,B,C are true but D is false
  3. A,C,D are true but B is false.
  4. A,B,C and D are all true.

Solution

In a semiconductor, at 0 K all the electrons are in the valence band and no electrons are there in the conduction band. At 0 K there are no free electrons but the number of electrons increases with the increase in temperature. As the temperature increases electrons gain kinetic energy, thus, breaks the covalent bonds and move to conduction band as the result number of free electrons and holes increases.The number of free electrons are less as they form a covalent bonds due to which lattice structure is created.

So, A,C,D are true but B is false.

Asked in: AP EAMCET 2022 (04 Jul Shift 2)

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