Question

If resistance R1 is 10K, V2 = – 2V, V1 = 3V and the diode is ideal then the current I through the circuit will be _________

(a) 0.2mA

(b) 0A

(c) 0.5mA

(d) 0.3mA

This question was posed to me in semester exam.

Question is from Ideal Diode Model-1 in section Diode Circuit of Analog Circuits

Answer 1

Right answer is (d) 0.3mA

To elaborate: In ideal diode model the diode is considered as a perfect conductor in forward bias and perfect insulator in reverse bias. That is voltage drop at forward bias is zero and current through the diode at reverse bias is zero.

The voltage V2 forward biases the diode so in effect V2 Vanishes. Also V1 is in reverse bias to the diode so it will not pass through diode. Therefore, effective current will be

(3V/10K) = 0.3mA.