In an LCR circuit, capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be changed from L to

Options

(a) 4 L
(b) 2 L
(c) L/2
(d) L/4

Correct Answer:

L/2

Explanation:

At resonance ω = 1 / √(LC)

Since ω is constant,

Therefore, LC = L’C’ = L’ × 2C

⇒ L’ = L / 2