Electronic Devices Question 256
Question: Assertion : If the temperature of a semiconductor is increased then it’s resistance decreases. Reason : The energy gap between conduction band and valence band is very small
[AIIMS 1997]
Options:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.
Show Answer
Answer:
Correct Answer: A
Solution:
In semiconductors the energy gap between conduction band and valence band is small (» 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.
