Question

Statement I: If the temperature of a semiconductor is increased, then its resistance decreases.
Statement II: The energy gap between conduction band and valence band in a semiconductor is very small.

• A. If both statements are true and statement II is the correct explanation of statement I
• B. If both statements are true but statement II is not the correct explanation of statement I
• C. If statement I is true but statement II is false
• D. If both statements are false

Answer 1

Answer: (A)

In semiconductors the energy gap between conduction band and valence band is small $(\approx 1 eV ) .$ Due to temperature rise, electron in the valence band gained thermal energy and may jump across the small energy gap, goes in to the conduction band. Thus conductivity increases and hence resistance decreases.