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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
How will you make an iron bar electromagnet? Draw a diagram showing the polarities of the electromagnet?
Tick the most appropriate answer.
Which of the following methods is used to magnetize a magnetic without touching it by a magnet?
Name the type of transformer shown in fig . What changes will you observe regarding the brightness of the lamp, if
(a) The no. of turns in the secondary is doubled?
(b) The part X of the transformer is removed?
( c) The core of the transformer is made out of copper?
(d ) The A.C. supply is replaced by D.C.?
State two factors on which the magnitude of an induced e.m.f. in the secondary coils of a transformer depends.
State two factors on which the strength of induced e. m.f. depends.
A straight current-carrying conductor is kept in a magnetic field. It Experiences a force. State three factors on which the magnitude of force Experienced by the conductor depends. Under what condition will the conductor Experience no force?
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.
(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.
Write the answer in your words.
How is an electromagnet made?
