# Impedance

Impedance is represented by the letter Z and is measured in terms of ohms. Impedance can be thought of as the "resistance" to the alternating current in a circuit.

Z = V/I

Z = √ R^{ 2} + X^{ 2} where X is reactance

Z = √ R^{ 2} + (X_{L}- X_{C})^{2}_{L} where X_{L} is Inductive Reactance and and X_{C} is Capacitive Reactance

Example 1:

If you have a circuit with 240V ac- circuit pulling 10A, what's the impedance of the said circuit.

Z = V/I

Z = 240V/10A

Z = 24 Ω

Example 2:

What's the impedance of a circuit (ac) with a reactance 12 Ω and a resistance of 8 Ω

Z = √ R^{ 2} + X^{ 2}

Z = √ (8 Ω)^{ 2} + (12 Ω)^{ 2}

Z = √64 Ω^{ 2} + 144 Ω^{ 2}

Z = √ 208 Ω^{ 2}

Z = 14.42 Ω

Example 3:

What's the impedance of an AC circuit with or resistance of 10 Ω, an inductive resistance of 20 Ω and capacitive reactance of 14 Ω

Recall that X_{L} is inductive resistance and X_{c} is capacitive reactance

Z = √ R^{ 2} + (X_{L}- X_{C})^{ 2}

Z = √ (10 Ω)^{ 2} + (20 Ω - 14 Ω)^{2}

Z = √ 100 Ω^{ 2} + (6 Ω)^{ 2}

Z = √ 100 Ω^{ 2} + 36 Ω ^{ 2}

Z = √ 136 Ω^{ 2}

Z = 11.66 Ω