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(A): While temperature of a semi conduct...

(A): While temperature of a semi conductor is increased its resistance decreases
(R): The energy gap between conduction band and valency band is very small and on heating the electrons can be shifted from valence band to conduction band.

A

Both 'A' and 'R' are true and 'R' is the correct explanation of 'A'

B

Both 'A' and 'R' are true and 'R' is not the correct explanation of 'A'

C

'A' is true and 'R' is false

D

'A' is false and 'R' is true

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to analyze the assertion and the reason provided, and determine their validity and relationship. ### Step 1: Understand the Assertion The assertion states that "while the temperature of a semiconductor is increased, its resistance decreases." - **Explanation**: In semiconductors, as the temperature increases, the thermal energy provided to the electrons allows more of them to jump from the valence band to the conduction band. This increase in the number of charge carriers (electrons) leads to an increase in conductivity, which in turn results in a decrease in resistance. ### Step 2: Understand the Reason The reason given is that "the energy gap between the conduction band and valence band is very small, and on heating, the electrons can be shifted from the valence band to the conduction band." - **Explanation**: This statement is true for semiconductors. The energy gap (band gap) in semiconductors is indeed small compared to insulators. Therefore, when the temperature rises, electrons can easily gain enough energy to overcome this small gap and move to the conduction band, contributing to increased conductivity. ### Step 3: Analyze the Relationship Now we need to determine if the reason correctly explains the assertion. - Since the assertion is true (the resistance of a semiconductor decreases with an increase in temperature) and the reason is also true (the small energy gap allows electrons to jump to the conduction band), and the reason explains why the assertion is true, we can conclude that both statements are correct and that the reason is a valid explanation for the assertion. ### Conclusion Both the assertion and the reason are true, and the reason is the correct explanation of the assertion. ### Final Answer - Assertion (A) is true. - Reason (R) is true. - R is the correct explanation of A.
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