Question

What is voltage across the resistor R if VA = -3V and VB = -5V is _________ (Use constant voltage drop model assumption and take VD = 0.5V)

(a) 0V

(b) -3V

(c) -5V

(d) -4V

I got this question by my school teacher while I was bunking the class.

This intriguing question comes from Constant Voltage Drop Model-2 topic in chapter Diode Circuit of Analog Circuits

Answer 1

The correct option is (a) 0V

For explanation I would say: In constant voltage drop model at forward bias diode can be replaced as a cell and in reverse bias diode can be avoided by considering the terminals are open. In above circuit both the diodes are reverse biased and can be considered as open circuit. Hence output voltage is 0V.