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Physics · 2026 · 3 marks
CBSE 2026 · Region 3 · Set 1 · Q24
(a) Discuss the behaviour of an inductor connected to (i) a dc source, and (ii) a high frequency ac source. (b) What is the phase relation between…
(a)
Discuss the behaviour of an inductor connected to (i) a dc source, and (ii) a high frequency ac source.
(b)
What is the phase relation between current and voltage in an ideal inductor connected to an ac source ? Draw a phasor diagram for the circuit.
Marking-scheme solution
(a)(i)
Initially inductor opposes the change in current and gradually current becomes steady.
(Alternatively)
Inductor behaves like a conductor.
(ii)
The magnetic field changes continuously around inductor and induces the back emf. At high frequency, the reactance becomes high, blocking the flow of current.
(b)
Current lags behind the voltage by an angle $\displaystyle \frac{\pi}{2}$ radian.
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CBSE Class 12 Physics past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.