Question

Photoelectric emission from a given surface of metal can take place when

the value of a ‘physical quantity’ is less than the energy of incident

photon. The physical quantity is: ​

Answer 1

Answer:

In photoelectric effect, the energy of the incident photon must be equal to the sum of the metal's work function and the photoelectron kinetic energy:

E (photon)=KE (electron)+Φ

Where, E is total energy of incident light, KE is the kinetic energy of the photon and Φ is work function.

So, the physical quantity is work function of surface.

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