A capacitor stores electric charge. Polarised capacitors must be connected the correct way round. They usually have larger values, 1µF and greater. See above for uses.
Aerial (Antenna) A device to receive or transmit radio signals. It is also known as an antenna.
The diagram shows a simple circuit of a battery, wires, a switch and a lamp. The switch works by breaking the circuit.
A capacitor stores electric charge. It can be used with a resistor in a timing circuit, for smoothing a supply (it provides a reservoir of charge) and can be used as a filter (blocking DC signals but passing AC signals). Unpolarised capacitors usually have small values, less than 1µF.