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प्रश्न
Why is soft iron generally used as the core of the electromagnet?
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उत्तर
(i) Soft iron has less retentivity so it acquires the magnetic properties only when the current flows through the coil wound on it and loses the magnetic properties as the current is switched off.
(ii) The soft iron intensifies the magnetic field of the electromagnet because of its high permeability.
संबंधित प्रश्न
The diagram shows a coil wound around a U shape soft iron bar AB.
1) What is the polarity induced at the ends A and B when the switch is pressed?
2) Suggest one way to strengthen the magnetic field in the electromagnet
3) What will be the polarities at A & B if the direction of current is reversed in the circuit?
State two ways of magnetising an iron piece?
How will you make an iron bar electromagnet? Draw a diagram showing the polarities of the electromagnet?
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.
Name and state the rule by which polarity at the ends of a current carrying solenoid is determined.
Name two factors on which the strength of magnetic field of an electromagnet depends and state how does it depend on the factors stated by you.
Name the material used for making the armature of an electric bell. Give a reason for your answer.
How does a magnetic field set up by a solenoid change when number of turns are increased?
State two advantages of an electromagnet over a bar magnet.
(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.
