Question

An AC circuit consists of a 220Omega resistance andn a 0.7 H choke. Find the power obsorbed from 220 V and 50 Hz source connected in this circuti if the resistance and choke are joined (a) In series (b) in parallel.

Answer 1

Given :

Resistance of circuit : 220 ohm

Inductance of circuit : 0.7H

Voltage = 220V

Frequency = 50Hz

To find :

Power absorbed if resistances are joined in

a)series

b)parallel

Solution :

a) Impedance of the circuit (Z) = √(R² + ω²L²)

                                              =√[220² + (2×3.14×50 ×0.7)²]

                                         Z =311 ohm

• I = Vrms / Z  = 220/311  = 0.707 A

• Cos∅ = R/Z = 220/311 = 0.707 A

• Power = Vrms×Irms×Cos∅

           =220 ×0.707×0.707

           =110.08 W

Power transmitted in case of series connection is 110.08W

b) Power transmitted in the circuit = (Vrms)² / R

                                                         =220² /220 = 220W

Power transmitted in case of parallel connection is 220W