Question

The incorrect statement among the following is (I = Intensity of incident radiation, f = frequency of incident radiation):

• A. Maximum kinetic energy of photoelectron varies linearly with \(f\)
• B. Maximum kinetic energy of photoelectron is independent of \(I\)
• C. Photoelectric current is directly proportional to \(I\)
• D. Stopping potential is proportional to \(I\)

Hint:

For photoelectric effect: \(K_\text{max} = h f - \phi\), current \(\propto I\), stopping potential independent of intensity.

Answer 1

The Correct Option is D

Step 1: Einstein's photoelectric relation.
K_max = h f - φ, where K_max depends linearly on frequency f, not on light intensity I.

Step 2: Photocurrent dependence.
The number of ejected electrons, and hence current, scales with photon count, i.e., proportional to intensity.

Step 3: Stopping potential.
V₀ = K_max/e depends only on frequency, independent of intensity.

Step 4: Identifying the false claim.
Statement (4) says stopping potential is proportional to intensity, which is incorrect.