Question
In order to emit the electron from the metallic surface, which physical methods are used to give the minimum energy? Explain.
✓
Answer
The minimum energy can be given by one of the following methods :
I. Thermionic emission
II. Field emission
III. Photoelectric emission.
I. Thermionic emission : Through thermionic emission, sufficient thermal energy can be given to the free electrons, so that they can come out of the metal.
II. Field emission : A strong electric field of the order of $10^8$ volts applied on a metal can emit electrons from the metal surface. As occurs in a spark plug.
III. Photoelectric emission : When light of appropriate frequency falls on a metal surface, electrons are emitted. These light generated electrons are called photoelectrons.
I. Thermionic emission
II. Field emission
III. Photoelectric emission.
I. Thermionic emission : Through thermionic emission, sufficient thermal energy can be given to the free electrons, so that they can come out of the metal.
II. Field emission : A strong electric field of the order of $10^8$ volts applied on a metal can emit electrons from the metal surface. As occurs in a spark plug.
III. Photoelectric emission : When light of appropriate frequency falls on a metal surface, electrons are emitted. These light generated electrons are called photoelectrons.
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