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Consider a metallic pipe with an inner r...

Consider a metallic pipe with an inner radius of 1 cm. If a cylindrical bar magnet of radius 0.8cm is dropped through the pipe, it takes more time to come down than it takes for a similar unmagnetised cylindrical iron bar dropped through the metallic pipe. Explain.

Text Solution

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When a cylindrical bar magnet is dropped through the pipe the magnetic flux linked with the metal pipe increase and eddy currents are produced and they oppose the motion of the magnet and hence acceleration of the falling magnet will be less than .g so the magnet will take more time.
If iron rod which is not magnetised is allowed to fall, no such effect is produced and hence it will fall with the same acceleration .g. and it will take less time for falling.
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  • A circular coil of radius 10 cm, 500 turns and resistance 2 Omega is placed with its plane, perpendicular to the horizontal component of the earth's magnetic field. It is rotated about its vertical diameter through 180^@ in 0.25 s. The induced e.m.f. in the coil is ..... (Take H_E=3.0xx10^(-5) T)

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