Question

Find the equivalent resistance of the network shown in the figure between the points A and B if
(i) `V_(A) gt V_(B) ` (ii) `V_(A) lt V_(B)`

Answer 1

(i) When `V_(A) gt V_(B)` the diode is forward biased. Hence, the resistance of diode will be taken as zero. So the equivalent resistance is
`=(4xx12)/(4+12) Omega=3 Omega`
(ii) When `V_(A) lt V_(B)`, the diode is reverse biased. Hence, there will be no current in the diode branch. So, the equivalent resistance is `12 Omega`