Question 450: AC fundamentals

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 $${\pi  \over 3}$$. If instead C is
removed from the circuit, the phase difference is again $${\pi  \over 3}$$
between current and voltage. The power factor of the circuit is :

Accepted Answer

The power factor for the LCR circuit will be :
When L is removed,
$$	an \phi  = {{\left| {{X_C}} ight|} \over R}$$
$$ \Rightarrow 	an {\pi  \over 3} = {{{X_C}} \over R}$$
 ...(i)
When C is removed,
$$	an \phi  = {{\left| {{X_L}} ight|} \over R}$$
$$ \Rightarrow 	an {\pi  \over 3} = {{{X_L}} \over R}$$
 ...(ii)
Since, X
L
= X
C
, the circuit is in resonance,
Z = R
Power factor = cos $$\phi $$ = $${R \over Z}$$
 = 1

Answer

0.5

Answer

1.0

Answer

$$ - $$
1.0

Answer

zero

AC fundamentals

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