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:

2.5 V

The correct answer is Option (3) → 2.5 V

Using Ohm's law,

$V_R=I.R$

$=0.1A×20Ω=2V$

The total voltage supplied across the source is,

$V_{source}=Voltage diode ($V_D$) + Voltage Resistor ($V_R$)

$=(0.5+2)$

$=2.5V$