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प्रश्न
Describe briefly three main useful application of eddy currents ?
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उत्तर
Application of Eddy currents:
(i) Induction furnace: When a piece of metal, which is to be converted into an alloy, is wound by the circular conducting coil, a high frequency alternating current is passed through the coil which in turns changes the magnetic flux associated with the metal. This produces strong eddy currents that generate a large amount of heat in the metal block and melts it easily.
(ii) Electric brakes: Electromagnets are placed in the trains just above the rails. Whenever these electromagnets are activated, eddy currents are produced in such a way that they oppose the motion and stop the train.
(iii) Induction motor: A rotating magnetic field produces strong eddy currents in the rotor of the motor, which starts rotating in the direction of the field.
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संबंधित प्रश्न
Two spherical bobs, one metallic and the other of glass, of the same size are allowed to fall freely from the same height above the ground. Which of the two would reach earlier and why?
How are eddy currents produced ?
A metal sheet is placed in front of a strong magnetic pole. A force is needed to ______________ .
(a) hold the sheet there if the metal is magnetic
(b) hold the sheet there if the metal is nonmagnetic
(c) move the sheet away from the pole with uniform velocity if the metal is magnetic
(d) move the sheet away from the pole with uniform velocity if the metal is nonmagnetic.
Neglect any effect of paramagnetism, diamagnetism and gravity.
Write two examples of their useful applications .
State applications of eddy currents.
Two simple pendula of length L and 4L are pulled aside to the right and are at rest so that they make an angle 30° with the vertical. They are then released simultaneously at time t = 0. The time after which they will be in phase is ______.
Which one is not an application of eddy current?
Consider a metallic pipe with an inner radius of 1 cm. If a cylindrical bar magnet of radius 0.8 cm 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.
