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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
State two ways of magnetising an iron piece?
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 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 _____.
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 principle of a D. C. motor.
What is dynomo (a.c. generator)? State the principle on which it works.
Point out three differences between an electromagnet and a bar (or permanent) magnet.
