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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
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.
principle of an electric motor ?
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.
Electric bell ______.
What is a permanent magnet? Give one use of it.
What will be the effect on the working of an electric bell if instead of a direct current an alternating current is used?
State the position of armature coil relative to the direction of magnetic field, in a D. C. motor when the deflecting couple acting an the coil is maximum.
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.
What are the factors that govern the magnitude of force acting on a current carrying conductor which is freely suspended in a magnetic field?
(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.
State the function of a split ring in D.C. motor.
