What is a rectifier ? Draw circuit diagram for a rectifier in which ouput is obtained continuously.

Explanation

Rectification. Rectification is the process of converting alternating voltage/current into direct voltage/current. A device used for this purpose is called rectifier and this phenomenon is called rectification.
Principle. It is based on the principle that a p-n junction diode conducts when it is forward biased and does not conduct when it is reverse biased.
Construction. The apparatus for rectification consists of two diodes `D_(1)` and `D_(2)` connected to two ends of the secondary of a step down transformer. Output is taken out from mid point of the secondary and common point N of two diodes. Ouput is taken out from ends of the load R.

Working. During the positive half of input `AC,D_(1)` is forward biased and `D_(2)` reverse biased. Hence the current flows through the upper circuit as shown. During negative half, lower portion `(D_(2))` is forward biased and upper `(D_(1))` is reverse biased.
Thus during each half, we get the current either from `D_(1)` or from `D_(2)`.
The output voltage is unidirectional having ripple contents.
Ripple factor of a rectifier `=("r.m.s of a.c.component")/("value of d.c. component")`
To smoothen the output electric filters are used. The electric filters are combination of inductors are capacitors. Some of the useful filters are L-filter and `pi`-filter.