In a conductor, the energy gap between valence and conduction bands is _____.

Question

Examoogle · Accepted Answer

Very small

Explanation: In a conductor, the energy bands (valence and conduction bands) overlap, which means there is effectively no energy gap (or a zero energy gap). Because there is no forbidden gap, electrons move freely from the valence band to the conduction band under the influence of an electric field.

Working Principle: According to the Band Theory of Solids, the electrical behavior of a material is determined by the overlap of its energy bands. In conductors, the valence band and conduction band overlap, meaning electrons exist in the conduction band at $0	ext{ K}$ without requiring thermal activation. This high availability of free electrons facilitates high electrical conductivity.

Key Formulas: $E_g = 0	ext{ eV}$ — Energy gap value for conductors due to band overlap.

Key Points: Conductors have no forbidden energy gap.; The valence band and conduction band overlap significantly.; Free electrons are abundant even at absolute zero temperature.; High conductivity is a direct result of the lack of a forbidden gap.

Advantages: Extremely high electrical conductivity.; Low resistivity.

Disadvantages: High susceptibility to short circuits.; Cannot be used to build switching devices like transistors directly without modification.

Applications: Electrical power transmission cables.; Printed circuit board (PCB) traces.

Additional Info: For semiconductors, the gap is typically around $1	ext{ eV}$ (e.g., $1.1	ext{ eV}$ for Silicon).. For insulators, the gap is typically $> 5	ext{ eV}$.

Answer: C is correct — Conductors exhibit an overlap between the valence and conduction bands, resulting in a forbidden energy gap of zero.

Exam Tip: Remember: Insulators have large gaps ($>5	ext{ eV}$), Semiconductors have small gaps ($sim 1	ext{ eV}$), and Conductors have overlapping bands ($E_g=0$).

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