Advertisements
Advertisements
Questions
State applications of eddy currents.
Write two applications of eddy current.
Advertisements
Solution
- 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.
APPEARS IN
RELATED QUESTIONS
State any two causes of energy loss in actual transformers.
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?
Give one example of use of eddy currents.
How are eddy currents produced ?
If the magnetic field outside a copper box is suddenly changed, what happens to the magnetic field inside the box? Such low-resistivity metals are used to form enclosures which shield objects inside them against varying magnetic fields.
A metallic bob A oscillates through the space between the poles of an electromagnet (See the figure). The oscillations are more quickly damped when the circuit is on, as compared to the case when the circuit is off. Explain.
Write two examples of their useful applications .
How can the disadvantages of eddy currents be minimized?
In which of the following devices, the eddy current is not used ______
Why and where are eddy currents are undesirable? How are they minimized?
How is Eddy current produced? How do they flow in a conductor?
Give the uses of Foucault current.
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 ______.
Identify the wrong statement.
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 ______.
If the length of a simple pendulum increases by 5%, then its period shall increase by ______.
For high frequency, capacity offers
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.
