Question

The relation AD – BC = 1, (where A, B, C and D are the elements of a transmission matrix of a network) is valid for ___________

(a) Both active and passive networks

(b) Passive but not reciprocal networks

(c) Active and reciprocal networks

(d) Passive and reciprocal networks

This question was posed to me during an internship interview.

This intriguing question originated from Series-Series Connection of Two Port Network topic in section Two-Port Networks of Network Theory

Answer 1

Correct option is (d) Passive and reciprocal networks

For explanation: AD – BC = 1, is the condition for reciprocity for ABCD parameters, which shows that the relation is valid for reciprocal network. The ABCD parameters are obtained for the network which consists of resistance, capacitance and inductance, which indicates that it is a passive network.