Magnetism Haitham N. Alahmad

Magnetism Magnetism is the force of attraction or repulsion in a material -The magnet is always points in a north-south direction. -The substance like iron,nickle and cobalt are strongly attracted by a magnet and are known as Ferromagnetic substance. 2

Magnetism -Every magnetic substance consist of very tiny magnets known as molecular magnets or domains. - In an un-magnetized piece of iron, the domains are present in all direction, where as in case of magnet the domains are arranged with their north poles pointing in one direction and the south poles pointing in the opposite direction. 3

Magnetism 4

Properties of magnet 1-A magnet has two poles N-pole and S-pole. 2-when a magnet is broken into two or more parts, each part is complete magnet. 3-Two poles of magnet cannot be separated. 5

Properties of magnet 4-The poles of magnet are of equal in strength. 5-The magnetism can be produced by magnetic induction and by electric current flowing in a coil. 6

Laws of magnetism -similar poles repel each other whereas dissimilar(opposite)poles attract each other. 7

Laws of magnetism -The force of attraction or repulsion between two magnetic poles is directly proportional to the product of their pole strengths -The force of attraction or repulsion between two magnetic poles is inversely proportional to the square of the distance between them. F=force of attraction or repulsion,m1,m2 are two magnetic poles and d=distance. 8

Laws of magnetism 9

Magnetic field -It is the space around the magnet, which attract or repels the other magnet. 10

Magnetic field It is made up of many lines of force, a line of force can be defines as the path taken by an independent n- pole moving outside from a north pole of the magnet to the s-pole and also from the s-pole to n-pole inside of the magnet. 11

Types of magnet 1-Bar magnet 12

Types of magnet 2-horseshoe shaped magnet(used in many parts of x-ray equipment) 13

Types of magnet 3-electromagnet 14

Magnetic effect due to current passing through a coil -There is magnetic effect associated with the passage of electric current in a coil. -The magnetic field is only present, when the current is ON and the direction depend on the direction of the current passing in the coil 15

Magnetic effect due to current passing through a coil 16