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What is rectifier ? Explain the use of p-n junction diode as a full wave rectifier. |
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Answer» Solution :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. |
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