Q.Draw a neat diagram of a full wave rectifier and explain it's working.

[!TLDR] A full wave rectifier uses a centre-tapped transformer with two diodes conducting on alternate half cycles, so current always flows through $R_L$ in the same direction, giving a continuous train of output pulses at TWICE the input frequency. [!ANSWER] Circuit: centre-tapped secondary AB (centre-tap P), diode $D_1$ from A and diode $D_2$ from B, both feeding $R_L$ (returned to P). $D_1$ conducts on the positive half cycle, $D_2$ on the negative half cycle, both driving current through $R_L$ in the same direction -- giving an unbroken train of output pulses.

Circuit diagram: the transformer's secondary winding has three connection points -- end A, end B, and a CENTRE-TAP P exactly midway between them (Fig. 16.4). The anode of diode $D_1$ connects to end A, and the anode of diode $D_2$ connects to end B; the cathodes of both diodes are joined together at a common node Q, from which the load resistor $R_L$ is connected back down to the centre-tap P, completing the circuit. Working: during the POSITIVE half cycle of the input (A at higher potential than P), $D_1$ is forward biased and conducts, sending current along the path A-P...-$R_L$-Q (through $D_1$); during the NEGATIVE half cycle (B at higher potential than P), $D_2$ is forward biased instead and conducts, sending current along the path B-P...-$R_L$-Q (through $D_2$). In BOTH cases, the current flows through $R_L$ in the SAME direction -- because the two diodes are wired so that whichever one is conducting always feeds the load the same way -- so unlike the half wave rectifier, no half-cycle of the input is wasted; every half cycle, positive or negative, produces one output pulse. The result is a continuous, unbroken train of output pulses across $R_L$ (Fig. 16.5, bottom trace), with no zero-output gaps at all between consecutive pulses. Since two pulses (one from $D_1$, one from $D_2$) are produced per full input cycle, the output/ripple frequency of a full wave rectifier is DOUBLE the input frequency (100 Hz for a 50 Hz mains input, per Example 16.1), and its theoretical maximum efficiency (81.2%) is exactly twice that of a half wave rectifier (40.6%). [!ANSWER] Circuit: centre-tapped secondary AB (centre-tap P), diode $D_1$ from A and diode $D_2$ from B, both feeding $R_L$ (returned to P). $D_1$ conducts on the positive half cycle, $D_2$ on the negative half cycle, both driving current through $R_L$ in the same direction -- giving an unbroken train of output pulses.

Describe the centre-tapped two-diode circuit, trace which diode conducts on which half cycle and show both drive $R_L$ in the same direction, then connect the resulting unbroken pulse train to the double-frequency ripple and doubled efficiency versus a half wave rectifier.

Drawing/describing the two diodes without the shared centre-tap connection, or without both cathodes joined at the same output node feeding $R_L$ -- the centre-tap is what lets a single load resistor receive current from either diode in the same direction, which is the entire mechanism that makes full-wave (rather than merely double half-wave) rectification work.