Question

An ac circuit consists of a resistor of 5 ohm and an inductor of 10 mH connected in a series with a 50 V (peak)/50 Hz supply. What capacitance should be connected in series with the circuit to obtain maximum current? What will be the maximum current?​

Answer 1

Answer:

Since the voltage is in phase with the current in series RLC circuit, this means the current is flowing at resonant frequency.

At resonance, Capacitive reactance is equal to inductive reactance i.e. X

C

=X

L

Given : R=5Ω L=50mH=0.05 H f

r

=50 Hz

Resonant frequency is given by f

r

=

2π

LC

1

∴ 50=

2π

0.05C

1

⟹ C=200μF

Impedance of circuit Z=

R

2

+(X

C

−X

L

)

2

⟹ Z=R (∵X

C

=X

L

)

Thus Z=5Ω