JEE Main 2024 · 5 April · evening · Single correct · +4 / −1
Which of the following statement is not true about stopping potential (V₀) ?
- (a) It depends upon frequency of the incident light.
- (b) It is 1 / e times the maximum kinetic energy of electrons emitted.
- (c) It increases with increase in intensity of the incident light.
- (d) It depends on the nature of emitter material.
Answer and solution
Answer (c) It increases with increase in intensity of the incident light.
Solution
Physics sir · 4 steps
Stopping potential only measures the fastest electron's energy, and intensity never makes any electron faster.
- What V0 measures. The stopping potential is the reverse voltage that just stops the most energetic photoelectrons. So eV₀ = Kₘₐₓ, which means V₀ = Kₘₐₓ/e.
eV₀ = hν - φ₀
- Read the equation. V₀ depends on the frequency ν and on the work function φ₀, which is fixed by the emitter material. Intensity does not appear anywhere in it.
- Role of intensity. Higher intensity means more photons per second, so more electrons come out and the photocurrent rises. Each photon still carries the same energy hν, so the fastest electron is no faster and V₀ stays the same.
- So. Statements (a), (b) and (d) are true. The false statement is (c): stopping potential does not increase with intensity.
The idea to keep. Frequency and material decide how fast the electrons come out; intensity decides how many come out. V₀ tracks speed, photocurrent tracks number.
Answer from the NTA final answer key. Solution by PrepWiser.