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

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Q: 23 (NDA-II/2017)
Electron emission from a metallic surface by application of light is known as

question_subject: 

Science

question_exam: 

NDA-II

stats: 

0,14,4,4,14,0,0

keywords: 

{'electron emission': [0, 0, 0, 1], 'photoelectric emission': [0, 0, 0, 1], 'thermionic emission': [0, 0, 0, 1], 'autoelectronic emission': [0, 0, 0, 1], 'high field emission': [0, 0, 0, 1], 'metallic surface': [0, 0, 0, 1], 'light': [16, 4, 34, 62]}

The correct answer is option 2: Photoelectric emission.

Explanation:

- Option 1: Thermionic emission refers to the emission of electrons from a heated metallic surface, not by the application of light.

- Option 3: High field emission, also known as field emission or Fowler-Nordheim emission, occurs when a strong electric field is applied to a material, causing electrons to be emitted.

- Option 4: Autoelectronic emission is not a recognized term and does not describe the process of electron emission from a metallic surface.

Photoelectric emission, as described in option 2, is the phenomenon where electrons are emitted from a metallic surface when light of a certain frequency or above is incident on it. This process is governed by the photoelectric effect, which was first explained by Albert Einstein. The energy of the incident photons is transferred to the electrons, causing them to overcome the surface barrier and escape from the material. The emitted electrons are called photoelectrons.

In conclusion, option 2, photoelectric emission, correctly describes the process of electron emission from a metallic surface by the application of light.