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प्रश्न
State the principle of a D. C. motor.
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उत्तर
It is based on the principle that when an electric current is passed through a conductor placed normally in a magnetic field, a force acts on the conductor as a result of which the conductor begins to move. The direction of the force is obtained with the help of Fleming’s left hand rule.
संबंधित प्रश्न
Suppose you are given a long bar magnet and you are asked to break it into four small magnets. Draw diagrams showing the polarities of each broken part.
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 the material used for making the armature of an electric bell. Give a reason for your answer.
Fill in the blanks by writing (i) Only soft iron, (ii) Only steel, (iii) Both soft-iron and steel for the material of core and/or magnet.
Electromagnet ______.
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.
How does a magnetic field set up by a solenoid change when a soft iron core is inserted inside solenoid?
State the energy change that takes’place 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.
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.
Point out three differences between an electromagnet and a bar (or permanent) magnet.
