Question

A photo sensitive metal is not emitting photo-electrons when irradiated. It will do so when threshold is crossed. To cross the threshold we need to increase(a) intensity(b) frequency(c) wavelength(d) None of these

Answer 1

ciao,
its frequency.
there is a minimum frequency below which no electrons are emitted however intense the light maybe.this ia threshold frequency and varies from meta to metal.
intensity determines only no. of electrons.
stay blessed ☺

Answer 2

Answer:

To cross the threshold we need to increase

( b) frequency,

so (b) is the correct answer

Explanation:

More is frequency of photon, more is energy.The higher the photon's frequency, the higher its energy. Equivalently, the longer the photon's wavelength, the lower its energy. Photon energy can be expressed using any unit of energy.