COMEDK · Physics · 30. Semiconductors

Pick out the correct statement from the following;

A Valance band is always completely filled, while conduction band is always partially filled
B The number density of free electrons in the valance band decides the strength of the electric current
C The maximum energy required to shift an electron from the conduction band to valance band is called energy band gap
D In a semiconductor no free electrons are found in the conduction band at 0 K

Verified Solution

Answer & Solution

Correct Answer

(D) In a semiconductor no free electrons are found in the conduction band at 0 K

Step-by-step Solution

Detailed explanation

At \(0\text{ K}\), all the electrons in a semiconductor are tightly bound to their respective atoms. The valence band is completely filled and the conduction band is completely empty. Since there are no free electrons in the conduction band at \(0\text{ K}\), a semiconductor…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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