Question

A series LCR circuit is connected to an ac voltage
source. When L is removed from the circuit, the
phase difference between current and voltage is pi by 3.
If instead C is removed from the circuit,
the phase difference is again pi by 3 between current
and voltage. The power factor of the circuit is:​

Answer 1

Explanation:

For only RC:- ϕ

RC

=

3

π

tan(

3

π

)=

R

X

c

⇒X

c

=

3

R

For only RL :- ϕ

RL

=

3

π

tan(

3

π

)=

R

X

L

⇒X

L

=

3

R

For RL:-

tan(ϕ)=

R

X

L

−X

C

=

R

3

R−

3

R

=0⇒ϕ=0⇒cosϕ=1