Question

41. The free electrons from a metal surface can be taken out by the process
A) thermionic emission
C) photoelectric emission
B) field emission
D) all of these​

Answer 1

Answer:

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Explanation:

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⭐ Answer⭐

The process by which, these free electrons break the bonding with metals and jumps into the vacuum is called electron emission. The amount of external energy required to remove an electron from the surface of a metal is called work function. Work function is measured in joules.

Answer 2

Answer:

A correct answer is an option (D): all of these.

Explanation:

• The process of emitting electrons from the surface of metals that is energized by an increase in temperature, radiation, or strong electrical field is called electron emission.
• Thermionic emission is defined as the discharge of negative charge i.e, electrons from a material that is stimulated by an increase in temperature. This method is used in electron tubes.
• Photoelectric emission is also a process of emitting electrons from metal surfaces by the process of light absorption by metals.

• Field emission is also another phenomenon of emitting electrons by application of a strong electric field to a cathode by a sharpened tip.

So, all three processes namely, thermionic emission, photoelectric emission, field emission are different types of electron emission and all of these processes can be used to take out free electrons from the surfaces of metals.

Hence the answer to the given question is an option (D).