Question

The expression of short circuit impedance Zsc is?

(a) Zsc=(Z1^2-4Z1Z2)/(2Z1-4Z2)

(b) Zsc=(Z1^2+4Z1Z2)/(2Z1+4Z2)

(c) Zsc=(Z1^2-4Z1Z2)/(2Z1+4Z2)

(d) Zsc=(Z1^2+4Z1Z2)/(2Z1-4Z2)

I have been asked this question by my college director while I was bunking the class.

The doubt is from Filter Networks topic in portion Filters and Attenuators of Network Theory

Answer 1

The correct choice is (b) Zsc=(Z1^2+4Z1Z2)/(2Z1+4Z2)

The best I can explain: On short circuiting the port 2 of T-section, we get the expression of short circuit impedance Zsc as Zsc=(Z1/2)+((Z1/2)xZ2)/((Z1/2)+Z2). On solving we get Zsc=(Z1^2+4Z1Z2)/(2Z1+4Z2).