The anode voltage of a photocell is kept fixed. The wavelength, λ of light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows.

The correct answer is Option (4)

When the anode voltage of a photocell is fixed and the wavelength of light falling n cathode increases, the plate current of the photocell decreases.

As the wavelength of the light increases, the energy of photon decreases. When the energy of the photon is less than the work junction, no electrons are ejected.