Under what conditions will an electric current exist in the circuit?

In order for an electric current to exist in a circuit, an electric field must be created in it.
An electric field in conductors is created and can be maintained for a long time by sources of an electric field.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.