Consider a magnet surrounded by a wire with an on/off switch $S (Figure) .$ If the switch is thrown from the off position $(open circuit)$ to the on position $(closed circuit),$ will a current flow in the circuit? Explain.

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Solution

As we know e.m.f. produced in a coil is rate of change of magnetic flux.

$e = - \frac{d ϕ}{d t} = \frac{d}{d t} (\to B . \to A)$

The magnet is stationary and hence the magnetic field does not change with time. Also, no part of the wire is moving, so area is also constant.

Hence, motional e.m.f. is zero. This means no electromotive force is produced and hence no current will flow in the circuit.

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Standard XII Physics

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Consider a magnet surrounded by a wire with an on/off switch S(Figure). If the switch is thrown from the off position (open circuit) to the on position (closed circuit), will a current flow in the circuit? Explain.

Consider a magnet surrounded by a wire with an on/off switch $S (Figure) .$ If the switch is thrown from the off position $(open circuit)$ to the on position $(closed circuit),$ will a current flow in the circuit? Explain.