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प्रश्न
State two advantages of an electromagnet over a bar magnet.
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उत्तर
Electromagnet can produce a strong magnetic field. Its polarity can be changed by reversing the direction of current.
संबंधित प्रश्न
Show with the aid of a diagram how a wire is wound on a U-shaped piece of soft iron in order to make it an electromagnet. Complete the circuit diagram and label the poles of the 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.
principle of 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.?
Answer the following in short.
Name a few common appliances that use electromagnets.
State the two properties of the magnetic lines of force around a circular coil.
A straight wire is held vertical and current is passed in it in the upward direction. A compass needle is kept near the wire in north of it. How is the needle deflected? What is the change in the deflection of the needle if the current in wire is reversed?
What will be the effect on the working of an electric bell if instead of a direct current an alternating current is used?
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.
How does a magnetic field set up by a solenoid change when cross-sectional area of solenoid is increased?
