NEET-XII-Physics
38: Electromagnetic Induction
- #11A conducting loop of face-area A and resistance R is placed perpendicular to a magnetic field B. The loop is withdrawn completely from the field. Find the charge which flows through any cross-section of the wire in the process. Note that it is independent of the shape of the loop as well as the way it is withdrawn.Ans : The magnetic flux through the coil is given by
ϕ = B.A = BA cos 0° = BA
It is given that the loop is withdrawn from the magnetic field.
∴ Final flux = 0
The average induced emf is given by
`` e=-\frac{∆\,\mathrm{\,\varphi \,}}{∆t}=\frac{\,\mathrm{\,BA\,}-0}{t}=\frac{BA}{t}``
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The current in the loop is given by
`` i=\frac{e}{R}=\frac{BA}{tR}``
The charge flowing through the area of the cross section of the wire is given by
`` q=it=\frac{BA}{R}``
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