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Power factor of an L-R series circuit is...

Power factor of an L-R series circuit is 0.6 and that of a C-R series circuit is 0.5. If the element (L. C, and R) of the two circuits are joined in series the power factor of this circuit is found to be 1. The ratio of the resistance in the L-R circuit to the resistance in the C-R circuit is

A

`6//5`

B

`5//6`

C

`4/(3sqrt(3))`

D

`(3sqrt(3))/4`

Text Solution

Verified by Experts

The correct Answer is:
D
`cosphi_(1)=0.6=3/5`
`tanphi_(1)=4/3=X_(C )/R_(2) …(1)`
`cosphi_(1)=0.5=1/2`
`tanphi_(2)=sqrt(3)=X_(C )/R_(2) …(2)`
From `(1)` and `(2) (3sqrt(3))/4=R_(1)/R_(2)`
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Knowledge Check

  • In L-C-R series circuit

    A
    current may achieve same value for two different value of frequency
    B
    current can not achieve same value for two different values of frequency
    C
    current is maximum for a maximum value of frequency
    D
    none of these

  • The power factor of an L-R series circuit is 0.5 and that of a C-R series circuit is 0.2. If the elements (L, C and R) of the two circuit are joined in series and connected to the same ac source, the power factor of this circuit is found to be 1. The ratio of the resistance in the L-R circuit to the resistance in the C-R circuit is

    A
    2
    B
    `sqrt2`
    C
    `2sqrt2`
    D
    4

  • The power factor of L-R circuit is-

    A
    `(omegaL)/( R)`
    B
    `(R)/(sqrt((omegaL)^(2)+R^(2)))`
    C
    `omega`LR
    D
    `sqrt(omegaLR)`

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