Question

The anode voltage of a photocell is kept fixed. The wavelength λ of the light falling on the cathode is gradually changed. The plate current vs. λ curve is

Answer 1

In a photocell, if a light of wavelength^ is incident on a cathode, then electrons are emitted, which constitute the photoelectric current. Photocell is based on the principle of photoelectric effect. As the wavelength of light changes, there is no change in number of electrons emitted and hence there is no change in current (plate current of photocell). Thus, the two wavelengths of incident light and plate current are independent to each other. Plate current depends on intensity of light used.

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