A diode having potential difference 0.5 V across its junction which does not depend on current, is connected in series with a resistance of 20 Ω across a source. If 0.1 A current passes through the resistor, the voltage across the source is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 2.5 V
The diode and the resistor are in series, so the source voltage is the sum of the potential differences across them. The drop across the diode is fixed at 0.5 V, and the drop across the resistor follows from Ohm’s law.
\( V_R = IR = 0.1\,\mathrm{A}\times20\,\Omega = 2\,\mathrm{V} \)
\( V = V_{\mathrm{diode}} + V_R = 0.5\,\mathrm{V} + 2\,\mathrm{V} = 2.5\,\mathrm{V} \)