RLC Circuits and Resonance - Engineering

Q1:

A 15  resistor, an inductor with 8  inductive reactance, and a capacitor with 12  capacitive reactance are in parallel across an ac voltage source. The circuit impedance is

A 12.7 

B 127 

C 4,436 

D 6,174 

ANS:A - 12.7 

Parallel : L & C
Z(lc) = 8i x (-12i)/(8i - 12i) = 24i

Parallel : Z(lc) & R
Ztotal = 24i x 15 / (24i + 15)
= 12.71, angle 32