06 Feb Magnetism
Physics tuition classes in Miracle Learning Centre is easy to understand and help you to improve in your grades. If you do not understand physics, you must definitely attend the physics tuition class at Miracle Learning Centre. Let us learn about magnetism in this physics tuition lesson.
These are some properties of magnets. A bar magnet has two poles. They are the North(-seeking) pole and South(-seeking) pole. A freely suspended magnet always points in a fixed direction.
A magnet can attract magnetic materials. A magnet has two poles. A freely suspended magnet always points in a fixed direction. Like poles repel and unlike poles attract. Repulsion is a sure test of the polarity of a magnet.
Magnetic Materials can be attracted by a magnet. Magnetic materials include iron, nickel, steel. Non-magnetic Materials cannot be attracted by a magnet. Non-Magnetic materials include rubber, wood, paper, clothes.
Soft iron and steel have different properties. These are the magnetic properties of soft iron. The soft iron gets strongly magnetised when magnetised by induction. Soft iron can be magnetised easily by a magnetic field. Soft iron can be demagnetised very easily, hence electromagnets are made of soft iron. There is loss of energy during magnetisation and demagnetisation in soft iron is very small. Thus, the core of transformer is made of soft iron.
These are the magnetic properties of steel. Steel is weakly magnetised when magnetised by induction. Steel requires strong magnetic field to get magnetized. Steel cannot be demagnetized easily hence permanent magnets are always made of steel. Loss of energy during magnetising and demagnetising of steel is very high.
The student at Miracle Learning Centre asked, “Is magnetism useful in our daily lives?”
The physics tuition teacher at Miracle Learning Centre replied,”Yes. Electromagnets are used in electric bells and refrigerators. Electromagnets are also used to separate magnetic and non-magnetic materials during recycling.”
Magnetic induction is the process of inducing magnetism in an unmagnetised magnetic material without any contact with the magnet used.
There are few methods of magnetization. The first method of magnetization is by stroking. The second method of magnetization is by the electrical method. A steel bar to be magnetized is placed inside a solenoid. When direct current (d.c.) is passed through the solenoid, the steel bar becomes a magnet.
There are few methods of demagnetization. The first method of demagnetization is by heating. Heating a magnet to a high temperature causes greatly increased vibrations of its atoms which will
totally destroy any magnetization of the material. The second method of demagnetization is by hammering. Hammering and dropping magnets can disarrange the tiny magnetic dipoles. The third method of demagnetization is by using an alternating current. A magnet to be demagnetized is placed inside a solenoid connected to an a.c. supply. The magnet will be demagnetized when it is slowly removed from the solenoid with the a.c. flowing in it.
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