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The self-inductance of a choke coil is 1...

The self-inductance of a choke coil is `10mH`. When it is connected with a `10 V DC` source, then the loss of power is `20 "watt"`. When it is connected with `10 "volt" AC` source loss of power is `10"watt"`. The frequency of `AC` source will be

A

80 Hz

B

100 Hz

C

120 Hz

D

220 Hz

Text Solution

Verified by Experts

The correct Answer is:
A
With DC, power, `P = V^(2)/R`
`R=(10)^(2)/20 = 5 Omega`
With AC power, `P= (V_(rms)^(2)R)/Z^(2) rArr Z^(2) = ((10^(2) xx 5)/10 = 50 Omega`
The impedance, `Z^(2) = R^(2)+4pi^(2)v^(2)L^(2)`
`50 = (5)^(2) + 4(3.14)^(2) xx v^(2) xx (10 xx 10^(-3))^(2)`
v=80 Hz
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