The friction between the copper wire and the magnet will generate electricity, but this is not the effect of friction, but the copper wire moving in the magnetic field of the magnet, cutting magnetic induction lines and generating an induced current.
The conditions for generating an induced current are:
1. Part of the conductor moves to cut the lines of magnetic field in the magnetic field, that is, the direction of movement of a conductor in a magnetic field is not parallel to the direction of the magnetic field lines.
2. When the circuit is closed, an induced voltage is generated at both ends of the conductor which cuts the magnetic field lines in the magnetic field, which is a power supply. If the circuit is closed, an induced current will be generated in the circuit. If the circuit is not closed, there is an induced voltage across the circuit, but no currentnt is induced in the circuit.
Copper wire is an electrode material. Lemon juice is an acidic electrolyte. Part of the toothpaste can be used as electrode material, and part receives heat from solar energy and decomposes to produce ions. that the ions in the lemon juice move in one direction to form an electric current. In copper wire, the directional movement of electrons also forms an electric current. These two circuits form a loop, so they can generate electricity.