• An electromagnet is a soft metal core made into a magnet by the passage of electric current through a coil surrounding it. The coil surrounding the soft metal is a solenoid.
• Solenoid is a coil of many turns of insulated copper wire wrapped in the shape of cylinder which has sits length much greater than its diameter. The magnetic field intensity of solenoid can be increased by increasing number of turns in solenoid, increasing strength of current through solenoid, placing a soft iron core along the axis of the solenoid and making soft iron core from thin wires i.e. laminated soft iron core.
• The two important type of electromagnets used for commercial purpose are I-shaped and U–shaped electromagnets.
In an I-shaped electromagnet, a straight bar is used as core inserted in a solenoid while in a U–shaped electromagnet; a U-shaped core is used. U-shaped electromagnet is made using two solenoids, one inserted in each arm of the U-shaped core.
• The magnetic field strength of an electromagnet depends on the amount of current passing through the coil, the number of turns in the coil and the nature of core material present inside the solenoid.
• Electromagnets are used in electric appliances such as electric bell, relays, in different medical and industrial purposes, etc.
• An electric bell is a mechanical bell that functions by means of an electromagnet. Electric bell works on the principle of electromagnetism. When switch is pressed, the circuit gets complete. The electromagnet present inside the bell attracts a metal hammer towards it hammering the gong making bell sound.
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How we can make a permanent magnet?Marks:2
Permanent magnet can be made by placing steel rod instead of soft iron bar inside the current carrying solenoid.
Solenoid behaves as a bar magnet.Marks:2
When an electric current passed through the solenoid then its one of the end behaves as a south pole and other end as north pole, which is similar to the bar magnet.
How does the strength of electromagnet will get affected by increasing the number of turns in a solenoid coil?Marks:1
By increasing the number of turns of the coil, the strength of magnet will increase.
What is an electric bell?Marks:1
Electric bell is a mechanical bell that functions by means of electromagnet.
The process of inducing magnetism in any magnetic material by passing electric current through itis known as electromagnetism.