Power dissipated in an LCR series circuit connected to an a.c source of emf ? is

Options

(a) ?ￂﾲ √ [ R² + ( L? – 1 / C?)² ] / R
(b) ?ￂﾲ [ R² + ( L? – 1 / C?)² ] / R
(c) ?ￂﾲR / √ [ R² + ( L? – 1 / C?)² ]
(d) ?ￂﾲR / [ R² + ( L? – 1 / C?)² ]

Correct Answer:

?ￂﾲR / [ R² + ( L? – 1 / C?)² ]

Explanation:

Power dissipated in series LCR;
P = IR = / (Z) R
= ?ￂﾲR / [ R² + ( L? – 1 / C?)² ]
where Z = √ R² + ( L? – 1 / C?)²
is called the impedance of the circuit.