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CGP EDU Academic Team
Published on: September 12, 2026
If rotational velocity of a dynamo armature is doubled, then induced e.m.f. will become
Text Solution
Verified by ExpertsThe correct answer is:
B
According to Faraday's law of electromagnetic induction, the induced electromotive force (e.m.f.) in a circuit is directly proportional to the rate of change of magnetic flux through the circuit.
- In a dynamo, the induced e.m.f. can be expressed as:
$$ E = N \cdot B \cdot A \cdot \omega $$
where E is the induced e.m.f., N is the number of turns of the coil, B is the magnetic field strength, A is the area of the coil, and \omega is the angular velocity (rotational velocity) of the armature. - If the rotational velocity \( \omega \) is doubled, then the new e.m.f. can be written as:
$$ E' = N \cdot B \cdot A \cdot (2\omega) $$
which simplifies to:
$$ E' = 2(N \cdot B \cdot A \cdot \omega) = 2E $$
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