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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.
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संबंधित प्रश्न
How will you make an iron bar electromagnet? Draw a diagram showing the polarities of the electromagnet?
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.
State two differences between an electromagnet and a permanent magnet.
Name the material of core in (a) an electric bell, (b) electromagnet, (c) a d.c. motor, (d) an a.c. generator and (e) a transformer.
Complete the following sentence :
On reserving the direction of current in a wire, the magnetic field produced by it gets _____.
What is a permanent magnet? Give one use of it.
State three factors which govern the speed of rotation of an electric motor.
What are the factors that govern the magnitude of force acting on a current carrying conductor which is freely suspended in a magnetic field?
State and explain Maxwell’s Cork Screw Rule.
(i) A straight wire conductor passes vertically through a piece of cardboard sprinkled with iron filings. Copy the diagram and show the setting of iron filings when a current is passed through the wire in the upward direction and the cardboard is tapped gently. Draw arrows to represent the direction of the magnetic field lines.
(ii) Name the law which helped you to find the direction of the magnetic field lines.
