Electron emission from a metallic surface by application of light is known as

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NDA (Held On: 10 Sept 2017) General Ability Test Previous Year paper

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Answer 1

CONCEPT:

The bundle of light ray is called as photon.
When photons fall on a metal surface then free electrons get ejected from the metal surface. This phenomenon is called as photoelectric emission.
When a high field is applied across a metal surface then ejection of electron is called as High field emission.
When ejection of electrons takes place due to heat is called as thermionic emission.
When ejection of electrons takes place due to its own energy is called as auto electronic emission.

EXPLANATION:

Here the emission of electrons takes place due to photons or light so the emission is called as photoelectric emission. Hence option 2 is correct.

Railways Solution Improvement Satya 10 June Madhu(Dia)

There is a certain minimum energy required to remove an electron from a metal surface. This energy is called as work function of that metal.