Question

If V1 is 5V and resistance R1 is 5KΩ and the cut-in voltage of the diode is 0.7V, what will be the voltage Vout across the diode? Take reverse saturation current as 10^-8A and operating temperature as 25°C.

(a) 0V

(b) -4.5V

(c) -5V

(d) -3.2V

I had been asked this question in an internship interview.

The doubt is from Characteristic Equation of Diode-2 in portion Diode Circuit of Analog Circuits

Answer 1

Correct option is (c) -5V

To elaborate: Since diode is in reverse bias mode voltage across diode will be almost the same as the applied voltage. Since the current in the circuit is in micro amperes voltage drop at R1 is negligible.