Q 12-14-168JEE MainJEE Main 2020 (7 Jan, Shift 2)Medium
In the figure, the potential difference between A and B is:
Answer: (A) $10$ V
The positive (longer) plate of the cell drives current from A through the diode in its forward direction, so the ideal diode conducts and acts as a plain wire.
Then the two $10\ \text{k}\Omega$ resistors between A and B are in parallel: $5\ \text{k}\Omega$. This is in series with the first $10\ \text{k}\Omega$:
$$I = \frac{30}{10 + 5}\ \text{mA} = 2\ \text{mA}$$
$$V_{AB} = 2\ \text{mA}\times5\ \text{k}\Omega = 10\ \text{V}$$
Solution by Sreeraj P, M.Sc Physics