Magnetic fields: When an electric current flows through a conductor, it creates a magnetic field around the conductor. The strength of the magnetic field is proportional to the amount of current flowing through the conductor. Magnetic fields can be used to induce electric currents in other conductors, or to exert a force on moving charges. For example, the magnetic field around a current-carrying wire can cause a compass needle to deflect.
Thermal effects: When an electric current flows through a conductor, it can cause the conductor to heat up. This is because the moving electrons in the conductor collide with the atoms of the conductor, transferring some of their energy to the atoms. The increased kinetic energy of the atoms causes them to vibrate more vigorously, which in turn increases the temperature of the conductor. The amount of heating depends on the amount of current flowing through the conductor and the resistance of the conductor. For example, a high-resistance wire will heat up more than a low-resistance wire when the same amount of current flows through them.
Light emission: When an electric current flows through certain materials, it can cause the material to emit light. This is the principle behind light-emitting diodes (LEDs). LEDs are semiconductor devices that emit light when an electric current is passed through them. The color of the light emitted by an LED depends on the material used to make the semiconductor. For example, red LEDs are made from gallium arsenide phosphide, while green LEDs are made from gallium phosphide.
