Question

What does charge required to overcome an electric field?

Answer 1

Free electrons moving from one region to another region have some kinetic energy.However, the free electrons do not have sufficient energy to escape from the metal surface. The strong attractive force of the nuclei prevents the free electrons , which try to escape from metal.
The free electrons need sufficient energy from external electric field to overcome the attractive force of nuclei. The free electrons, which overcomes the attractive force of nuclei escape easily from the metal surface.




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