JEE Main 2023 · 25 January · evening · Single correct · +4 / −1
Given below are two statements :
Statement I : Stopping potential in photoelectric effect does not depend on the power of the light source.
Statement II : For a given metal, the maximum kinetic energy of the photoelectron depends on the wavelength of the incident light.
In the light of above statements, choose the most appropriate answer from the options given below
- (a) Both Statement I and Statement II are incorrect
- (b) Statement I is correct but Statement II is incorrect
- (c) Both Statement I and Statement II are correct
- (d) Statement I is incorrect but Statement II is correct
Answer and solution
Answer (c) Both Statement I and Statement II are correct
Solution
Physics sir · 4 steps
Power decides how many photons arrive; frequency decides how much energy each one carries.
- Einstein's equation. One photon gives its whole energy hν to one electron. The fastest electron leaves with whatever is left after paying the work function φ, and the stopping potential V₀ is what it takes to stop that electron.
eV₀ = Kₘₐₓ = hc/λ - φ
- Statement I. Raising the power at a fixed wavelength sends more photons each second, but each photon still carries hc/λ. More electrons come out, so the photocurrent grows, but V₀ stays the same. Correct.
- Statement II. For a given metal φ is fixed, so Kₘₐₓ changes only through hc/λ. A shorter wavelength gives faster electrons. Correct.
- So. Both statements are correct, which is option (c).
The idea to keep. In the photoelectric effect, intensity or power changes only the number of electrons, that is, the current. Frequency or wavelength sets Kₘₐₓ and V₀, through eV₀ = hν - φ.
Answer from the NTA final answer key. Solution by PrepWiser.