Question

A series LCR circuit with R = 22$\Omega$ L =1.5H and C= 40$\mu F$is connected to a variable frequency 220V ac supply. When the frequency of the supply equals the natural frequency of the circuit Whet is the average power transferred to the circuit in one complete cycle?

• A. 2000W
• B. 2200W
• C. 2400W
• D. 2500W

Answer 1

Answer: (B)

2200W

Answer 2

:When the frequency of the supply equals to the natural frequency of circuit, resonance occurs.

$\therefore Z = R = 22\Omega$

and $I_{rms} = \frac{V_{rms}}{Z} = \frac{220}{22} = 10A$

Average power transferred per cycle,

$P = V_{rms}I_{rms}\cos 0^{o}$

$= 220 \times 10 \times 1 = 2200W$