Question

A student wants to use two p-n junction diodes to convert alternating current into direct current. Draw the labelled circuit diagram she would use and explain how it works.

Answer 1

The student will use a full wave rectifier. 

Two diodes are used to give rectified O/P corresponding to both positive as well as negative half cycles.

When the voltage at A with respect to the centre tap is positive, and the voltage at B is negative. Then, D₁ is forward biased and D₂ is reversed biased. Hence, D₁ conducts and D₂ does not.

When the voltage of A becomes negative, then B becomes + ve. Therefore, D₁ does not conduct and D₂ conducts. Hence, we obtain output voltage during both the positive as well as negative half of cycle.