AMPLIFICATION. In radio communication amplification may be considered as a magnification or enlargement of energy which takes place in an electrical circuit. It is a f unction by which the intensity of the electrical variations in the output cir cuit are increased without altering their wave forms. Amplifica tion is essentially a relay action. In radio reception, the com paratively weak signal voltages impressed on a vacuum tube amplifier produce in the output circuit a correspondingly in creased amount of power which is drawn from the "B" battery or other source of power in the plate circuit. The amplification factor is a number which expresses the magnitude of this effect.