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प्रश्न
State three factors which govern the speed of rotation of an electric motor.
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उत्तर
(i) The strength of current in the coil,
(ii) The number of turns in the coil,
(iii) The strength of the magnetic field.
संबंधित प्रश्न
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.
Answer the following in short.
Name a few common appliances that use electromagnets.
How does a magnetic field set up by a solenoid change when strength of current in the solenoid is decreased?
Why is soft iron generally used as the core of the electromagnet?
State two advantages of an electromagnet over a bar magnet.
The primary windings of a step-up transformer are usually made of thicker wire than the secondary. Explain.
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.
A current-carrying solenoid is suspended so as to freely rotate in a horizontal plane. State in what direction will it rest. Give a reason for your answer.
or
When a solenoid that is carrying current is freely suspended, it comes to rest in a particular direction. Why does this happen?
Which magnet will you use?
Iron is to be separated from trash.
