What is meant by the terms :
(i) a full wave rectifier ?
(ii) an amplifier ?
(iii) an oscillator?

Explanation

Full wave rectifier : It converts alternating current into direct current and utilizes both halves of each cycle of alternating current. In this, complete conversion of a.c. to d.c. takes place.
(ii) An amplifier : A device which amplify a signal. A junction diode cannot amplify a signal. A transistor consisting of two p-n junctions, one forward biased and the other reverse biased, is used to amplify a weak signal.
(iii) An oscillator : It is a device that generates electrical oscillations of constant amplitude and of desired frequency, without any external input.