KCET · Physics · Current Electricity
Given below are two statements:
Statement-I: The resistivity of a conductor is independent of its temperature.
Statement-II: The resistivity of a semiconductor decreases with increase in temperature.
Select the correct option.
- A Both Statement I and Statement II are false
- B Both Statement I and Statement II are true
- C Statement I is true but Statement II is false
- D Statement I is false but Statement II is true
Answer & Solution
Correct Answer
(D) Statement I is false but Statement II is true
Step-by-step Solution
Detailed explanation
The resistivity of a conductor increases with an increase in temperature due to an increase in the collision frequency of free electrons with the lattice ions. Thus, Statement-I is false.
The resistivity of a semiconductor decreases with an increase in temperature because the number density of charge carriers (electrons and holes) increases exponentially with temperature, which dominates over the effect of increased collision frequency. Thus, Statement-II is true.
Therefore, Statement I is false but Statement II is true.
Answer: Statement I is false but Statement II is true
The resistivity of a semiconductor decreases with an increase in temperature because the number density of charge carriers (electrons and holes) increases exponentially with temperature, which dominates over the effect of increased collision frequency. Thus, Statement-II is true.
Therefore, Statement I is false but Statement II is true.
Answer: Statement I is false but Statement II is true
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