Question

Potential difference between A and B in given figure is

• A. 0 V
• B. 7.5 V
• C. 10 V
• D. 15 V

Answer 1

The correct option is B 7.5 V

Resistance of diode in forward bias is very small compared to $10k\Omega$ and so it is neglected.
$R_{eq}$ for the battery is $20k\Omega$.
$V=i{R}_{eq}$
$\Rightarrow$ 30= $i\times 20k\Omega \Rightarrow i=\frac{3}{2}mA$
Current divides equally into the two branches because of equal resistances, so through AB, the current is $\frac{i}{2}=\frac{3}{4}mA$
$V_{AB}=\frac{3}{4}mA\times 10k\Omega =7.5V$