Circuit Theorems in AC Analysis - Engineering

Q1:

Referring to the given circuit, find ZTH if R is 15 k and RL is 38 k.

A 89.82 –51.3° k

B 19.2 –38.3° k

C 9.38–51.3° k

D 180 –38.3° k

ANS:C - 9.38–51.3° k

In getting Zth all resistors must be considered.

1. However, XL is in parallel with 0 ohms (shorted part of the source), making it also zero so it will be disregarded.
4(0)/4+0 = 0

2. If not stated, automatically consider RL as your Vout, thus it's open.

3. This will leave us with Xc/R.
4. ZTH = 9.37 ∠ 51.3°.