Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the most appropriate answer from the options given below :
- Both (A) and (R) are true and (R) is the correct explanation of (A).
- Both (A) and (R) are true but (R) is not the correct explanation of (A).
- (A) is false but (R) is true
- (A) is true but (R) is false
Answer
(2) Both (A) and (R) are true but (R) is not the correct explanation of (A).
Solution
(A): As per NCERT, the photoelectric current can be reduced to zero by applying a sufficiently large retarding (negative) potential; at the stopping potential V0 even the fastest photoelectrons are stopped. So (A) is true.
(R): Einstein's equation eV0 = h - 0 V0 = he - 0e
V0 varies linearly with frequency . So (R) is true.
(R) only tells how the stopping potential depends on frequency; it does not explain why a negative potential suppresses the emission. So (R) is not the correct explanation of (A).
Answer: (2)