The circuit shown in the figure contains two diodes, each with a forward resistance of \( 30\,\Omega \) and an infinite reverse resistance. If the battery is 3 V, the current through the \( 50\,\Omega \) resistor is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 0.02 A
A forward-biased diode conducts, and here it acts as a \( 30\,\Omega \) resistance. A reverse-biased diode has infinite resistance and carries no current.
From the figure, the two diodes in the upper branches face opposite ways. So one of them is forward biased and the other is reverse biased. Only one upper branch carries current. That current passes through the \( 50\,\Omega \) resistor, the conducting diode and the \( 70\,\Omega \) resistor of its branch, all in series.
The total resistance in the path is:
\( \begin{aligned} R &= 50\,\Omega+30\,\Omega+70\,\Omega \\ &= 150\,\Omega \end{aligned} \)
The current through the \( 50\,\Omega \) resistor is:
\( \begin{aligned} I &= \frac{V}{R} \\ &= \frac{3\,\mathrm{V}}{150\,\Omega} \\ &= 0.02\,\mathrm{A} \end{aligned} \)