12. including a full-wave rectifier in an ac circuit will yield a/an current.

The full wave rectifier is a circuit that converts an ac voltage into a pulsating dc voltage by using every half-cycle of the input voltage.
Including a full-wave rectifier in an AC circuit will yield a  continuous direct current.
A full wave rectifier consists of two diodes, one for each half of the wave and a multiple winding transformer.

Aform of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space. there are many forms of  electromagnetic  energy including gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.