Advertisements
Advertisements
प्रश्न
How does an electromagnet differ forma permanent magnet?
उत्तर
| Electromagnet | Permanent magnet | ||
| 1. | It is a temporary magnet. |
1.
|
As the name suggests, it is a permanent magnet. |
| 2. | It can produce very strong magnetic force. | 2. | It produces a comparatively weak magnetic field. |
| 3. | Its polarity can be changed by changing the direction of current in the coil. | 3. | Its polarity is fixed and cannot be changed. |
| 4. | Its strength can be changed by changing the number of turns or by changing the current. | 4. | Its strength cannot be changed. |
APPEARS IN
संबंधित प्रश्न
The magnetic flux through a loop is varying according to a relation `phi = 6t^2 + 7t + 1` where `phi` is in milliweber and t is in second. What is the e.m.f. induced in the loop at t = 2 second?
Explain why, an electromagnet is called a temporary magnet.
When a wire is moved up and down in a magnetic field, a current is induced in the wire. What is this phenomenon known as?
Figure shows a long U-shaped wire of width l placed in a perpendicular magnetic field B. A wire of length l is slid on the U-shaped wire with a constant velocity v towards right. The resistance of all the wires is r per unit length. At t = 0, the sliding wire is close to the left edge of the U-shaped wire. (a) Calculate the force needed to keep the sliding wire moving with a constant velocity v. (b) If the force needed just after t = 0 is F0, find the time at which the force needed will be F0/2.0
State Lenz’s law.
A layer of atmosphere that reflects medium frequency radio waves which is ineffective during night, is ______.
The instrument that use to defect electric current in the circuit is known as ____________.
Induced current flows through a coil ______.
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)
Which type of force is experienced by a moving charge in a magnetic field?
