Chapter 12 : Magnet and its Properties
A magnet is a material that can exert a noticeable force on other materials without actually contacting them.
This force is known as a magnetic force and may either attract or repel.
Like poles repel, unlike poles attract.
Magnetic forces attract only magnetic materials or iron.
Magnetic forces act at a distance.
While magnetized, temporary magnets act like permanent magnets.
A coil of wire with an electric current flowing through it becomes a magnet.
Putting iron inside a current-carrying coil increases the strength of the electromagnet.
A changing magnetic field induces an electric current in a conductor.
A charged particle experiences no magnetic force when moving parallel to a magnetic field.
But when it is moving perpendicular to the field it experiences a force perpendicular to both the field and the direction of motion.
A current-carrying wire in a perpendicular magnetic field experiences a force in a direction perpendicular to both the wire and the field.
Every magnet has at least one North Pole and one South Pole, by convention.
We say that the magnetic field lines leave the North end of a magnet and enter the South end of a magnet.
If you take a bar magnet and break it into two pieces, each piece will again have a North Pole and a South Pole.
If you take one of those pieces and break it into two, each of the smaller pieces will have a North Pole and a South Pole.
No matter how small the pieces of the magnet become, each piece will have a North Pole and a South Pole
Topics covered in this snack-sized chapter:
Magnets are nothing but a magnetized iron rod.
In iron rod all molecules are in opposite direction but when it turns into magnet electron arrange in one direction. That is the reason for polarity.
When an external magnetic field is applied, the magnetic fields of the individual domains line up in the direction of the external field
Iron rod magnetize by electric energy, which is then known as Electromagnet.
An electromagnet is simply a coil of wires which, when a current is passed through, generate a magnetic field, as below.
Ferromagnetism - When a ferromagnetic material is placed near a magnet, it will be attracted toward the region of greater magnetic field.
If a piece of iron is placed within a strong magnetic field, the domains in line with the field will grow in size as the domains perpendicular to the field will shrink in size