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Question:

In the given figure, a diode D is connected to an external resistance R=100Ω and an emf of 3.5 V. If the barrier potential developed across the diode is 0.5 V, the current in the circuit will be?

40 mA

35 mA

20 mA

30 mA

Solution:

Net potential across the resistor is difference of the emf and the barrier potential.
∴iR = ε − Vbarrier = 3.5 − 0.5 = 3
⇒i = 3/100 A = 30 × 10⁻³ A = 30 mA.