Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R :
Assertion A : In the photoelectric effect, the electrons are ejected from the metal surface as soon as the beam of light of frequency greater than threshold frequency strikes the surface.
Reason R: When the photon of any energy strikes an electron in the atom, transfer of energy from the photon to the electron takes place.
In the light of the above statements, choose the most appropriate answer from the options given below :
Assertion A : In the photoelectric effect, the electrons are ejected from the metal surface as soon as the beam of light of frequency greater than threshold frequency strikes the surface.
Reason R: When the photon of any energy strikes an electron in the atom, transfer of energy from the photon to the electron takes place.
In the light of the above statements, choose the most appropriate answer from the options given below :
- (A)Both A and R are correct but R is NOT the correct explanation of A
- (B)A is correct but R is not correct✓ Correct
- (C)Both A and R are correct and R is the correct explanation of A
- (D)A is not correct but R is correct
Answer: (B)
Solution
Assertion A is correct: in the photoelectric effect, electrons are ejected instantaneously when light of frequency greater than the threshold frequency strikes the metal surface. This is a key observation that supports the quantum nature of light. Reason R is incorrect: energy transfer does NOT occur for photons of any energy. Only photons with energy (work function) can eject electrons. Photons with energy below the threshold are absorbed but do not cause electron ejection, regardless of intensity or duration. Therefore, A is correct but R is not correct.
JEE Main · 2023 · 11 Apr 2023 · Shift 1 · Single correct option