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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
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.
The magnetic flux through a coil having 100 turns decreases from 5 milli weber to zero in 5 second. Calculate the e.m.f. induced in the coil.
Describe briefly one way of producing an induced current in a coil. State one factor that determines the magnitude of induced e.m.f.
How does a magnetic field set up by a solenoid change when number of turns are increased?
Why is soft iron generally used as the core of the electromagnet?
State the factors that can increase the speed of rotation of the coil in a D.C. motor.
State the position of armature coil relative to the direction of magnetic field, in a D. C. motor when the deflecting couple acting and the coil is minimum.
Point out three differences between an electromagnet and a bar (or permanent) magnet.
State the function of a split ring in D.C. motor.
