Advertisements
Advertisements
प्रश्न
A light metal disc on the top of an electromagnet is thrown up as the current is switched on. Why? Give reason.
Advertisements
उत्तर
When the current begins to grow through the electromagnet, the magnetic flux through the disc begins to increase. This sets up eddy current in the disc in the same direction as that of the electromagnetic current. Thus, if the upper surface of electromagnet acquires N-polarity, the lower surface of the disc also acquires N-polarity. As same magnetic poles repel each other, the light metallic disc is thrown up.
APPEARS IN
संबंधित प्रश्न
The device used for producing electric current is called _________.
A circular coil of cross-sectional area 200 cm2 and 20 turns is rotated about the vertical diameter with angular speed of 50 rad s−1 in a uniform magnetic field of magnitude 3.0 × 10−2T. Calculate the maximum value of the current in the coil.
Write some of the important uses of electromagnets.
In which of the following case does the electromagnetic induction occur?
A loop of wire is held near a magnet.
List some of the practical applications of an electromagnet.
What for an inductor is used? Give some examples.
A cylindrical bar magnet is kept along the axis of a circular coil. If the magnet is rotated about its axis, then ____________.
An expression for oscillating electric field in a plane electromagnetic wave is given as Ez = 300 sin(5π × 103x - 3π × 1011t)Vm-1 Then, the value of magnetic field amplitude will be ______. (Given: speed of light in Vacuum c = 3 × 108 ms-1)
How were electricity and magnetism considered for a long time?
What happens when the current in a nearby solenoid coil is switched on or off?
