Question

The circuit shown in the figure contains two diodes each with a forward resistance of $30\Omega$ and with infinite backward resistance. If the battery is 3 V, the current through the $50\Omega$ resistance is

• A. zero
• B. 0.01 A
• C. 0.02 A
• D. 0.03 A

Answer 1

Answer: (C)

In the circuit the upper diode $D_1$ is reverse biased and the lower diode $D_2$ is forward biased. Thus there will be no current across upper diode junction. The effective circuit will be as shown in figure.
Total resistance of circuit
$R=50\Omega +70\Omega +30\Omega =150\Omega$
Current in circuit, $I=\frac{V}{R}=\frac{3V}{150\Omega }=0.02A$