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प्रश्न
State applications of eddy currents.
उत्तर
Applications:
- Dead-beat galvanometer: The coil is wound on a light aluminium frame in a pivoting moving-coil galvanometer for measuring current. The coil is swiftly brought to rest by the rotation of the metal frame in the magnetic field, which causes eddy currents in the frame that oppose the rotation. This causes the galvanometer to stop working.
- Electric brakes: When a conducting plate is pushed into or pulled out of a magnetic field fast, the interaction between the moving conductor's eddy currents and the field slows down the velocity. This property of eddy currents is used in vehicles as a method of braking.
संबंधित प्रश्न
State any two causes of energy loss in actual transformers.
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Give one example of use of eddy currents.
How are eddy currents produced ?
Describe briefly three main useful application of eddy currents ?
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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.
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The plane in which eddy currents are produced in a conductor is inclined to the plane of the magnetic field at an angle equal to ______.
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A constant retarding force of50 N is applied to a body of mass 20 kg moving initially with a speed of 15 ms-1. How long does the body take to stop?
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 ______.
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Eddy currents are also known as ______
A metal plate is getting heated. It can be because ______.
- a direct current is passing through the plate.
- it is placed in a time varying magnetic field.
- it is placed in a space varying magnetic field, but does not vary with time.
- a current (either direct or alternating) is passing through the plate.
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.
