If both the resistance and the inductance in an LR AC series circuit are doubled the new impedance will be

Options

(a) halved
(b) fourfold
(c) doubled
(d) quadrupled

Correct Answer:

doubled

Explanation:

For L-R circuit, Z = √(R² + Xʟ²)

Z₁ = √(R₁² + Xʟ₂²)

Z₂ = √(R₂² + Xʟ₂²)

Given, R₂ = 2R and Xʟ₂ = 2Xʟ

Then, Z₂ = √[(2R)² + (2Xʟ)²] = 2 Z₁