(a) Students wants to use tow p-m jusnction diodes to convnet alternating current into direct current . Draw the labelled circuit she would use and explain how it works.
(b) Give the truth table and circuit symbol for NAND gate.

Explanation

(a) To convert alternating current into direct current she should use full wave rectifier. The circuit diagra and working of full wave rectifier is as shown :

In this circuit there are two diodes in oder to rectify both the cycle of a . c `I//P`. For this centre tap transformer `(phi^("mer"))` is used .
(i) Operation during positive half cycle : During positive half cycle `D_(1)` diode is forward biasd and hence, wil conduct `Id_(1)` flows through `R_(L)`. In this cycle diode. `D_(2)` is reverse baised and hence, does not conduct. Only `D_(1)` supplies the load current `I_(L) = Id_(I)` .

(ii) Operation during negative half-cycle : In the negavtive half cycle polarity reverse and A becomes- ve and `B^(-)` becomes - ve and `B^(-)` becomes `+ ve` hence, the diode `D_(1)` does not conduct but `D_(2)` conducts being forwards biased current in the ciruit is as shown due to `D_(2)` .