Question

In a series LCR circuit, obtain an expression for the resonant frequency

Answer 1

In a series LCR circuit,

From this equation, we may observe that when ω = 0, I becomes O, and again when

ω = ∞,I = 0

∴ This implies there must be a value of ω at which I is maximum.

so when I is maximum,

 

is minimum

For this either 

So when ωL - 1/ωc = 0, this is called resonance condition.

∴ At resonance,

This is the required expression for resonant frequency.