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प्रश्न
What is a permanent magnet? Give one use of it.
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उत्तर
A permanent magnet is a magnet made from steel such that once magnetized, it does not lose its magnetism easily. Use: It is used in the galvanometer.
संबंधित प्रश्न
You are given an iron nail, a torch cell, and a long piece of insulated copper wire. With the help of a labelled neat diagram, describe in steps how you will make the nail, an electromagnet.
Name two factors on which the strength of magnetic field of an electromagnet depends and state how does it depend on the factors stated by you.
What is an electric motor?
Name the type of transformer shown in fig . What changes will you observe regarding the brightness of the lamp, if
(a) The no. of turns in the secondary is doubled?
(b) The part X of the transformer is removed?
( c) The core of the transformer is made out of copper?
(d ) The A.C. supply is replaced by D.C.?
State the two properties of the magnetic lines of force around a circular coil.
State the purpose of the iron core.
How does a magnetic field set up by a solenoid change when strength of current in the solenoid is decreased?
State three factors which govern the speed of rotation of an electric motor.
State the energy change that takes’place in a D. C. motor.
State the factors, on which depends the magnitude of the force acting on current carrying conductor, when it is kept in a magnetic field perpendicular to it.
