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A coil has reactance of 100 \(\Omega\) when the frequency is 50 Hz. If the frequency becomes 150 Hz, then the reactance will be:

1. 100 \(\Omega\)
2. 300 \(\Omega\)
3. 450 \(\Omega\)
4. 600 \(\Omega\)

Correct answer: 300 \(\Omega\)

Solution

For a coil, inductive reactance is \(X_L=2\pi fL\), so it is proportional to frequency. When frequency increases from 50 Hz to 150 Hz, it becomes three times, i.e. 300 \(\Omega\).

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