22-08-2012, 11:52 AM
Viva voice Questions & Answers
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1. Define Rectifier?
An electrical circuit used to convert AC into DC current. A rectifier is a diode that causes the current to flow in only one direction. The output of the rectifier is essentially half-AC current, which is then filtered into DC.
2. Define Full wave Rectifier?
A rectifier that flattens both positive and negative halves of the incoming AC to pulsating DC. This design is used more often because it is more efficient than a half-wave rectifier.
3. Define construction of Full wave Rectifier?
Full wave rectifier is a circuit which rectifies both half cycles of the a.c. when P of 1st diode is positive, the 1st diode is forward biased and will conduct. Now the 2nd diode will not conduct as it is reverse biased. In all the half cycles either of the two diodes will be conducting. The efficiency of a full wave rectifier is about 81.2 %, twice the efficiency of a half wave rectifier.
4. What are the merits of Full Wave Rectifier?
major advantage of full-wave and bridge rectifiers over half-wave rectifiers is the ease of filtering their output voltages. You can now see the reason for this. The ripple frequency is doubled; therefore, the time period the capacitor is allowed to discharge is cut in half. This means that the capacitor discharges less. Thus, ripple amplitude is less, and a smoother output voltage occurs.
5. What is the major disadvantages of Full Wave Rectifier?
The only disadvantage is that the peak voltage in a full-wave rectifier is only half the peak voltage in a half-wave rectifier. This is because the secondary of the power transformer in a full-wave rectifier is center tapped; therefore only half the source voltage goes to each diode.
6. what are the futures of Full Wave Rectifier [center-tap]?
center-tap :A wire connected to the midpoint of a transformer secondary winding. This allows the transformer to use different turns ratios.