Magnetism

Magnetism

by Cg Roszy

​2 types of magnets

​Natural magnet - magnet that have property of attracting iron and this magnet is a weak magnet.

​

​Artificial magnet - made of materials like Iron, Nickel, Cobalt and Steel where there can be easily magnetised (easily can be a magnet). This magnet is a strong magnet.

​Magnet

• ​Magnet has two poles.

• A freely hanging magnets point in a north-south direction

​A magnet suspended freely comes to rest only in North-South direction. Why?

​This is because the earth behaves like a huge bar magnet.

​Like poles repel each other 

​Unlike poles attract each other 

​Magnetic materials

• ​Materials that are attracted by a magnet.

• ​Example are iron, nickel, cobalt and steel

​ Non-magnetic materials

• ​Materials that are not attracted by a magnet.

• ​Example are rubber, plastics, copper, wood and aluminium.

​To distinguish between a magnet and a magnetic material

​•When a magnetic materials is placed near a magnet, both of its ends are attracted to it

•When a magnet is placed near a magnet, one of its end will attract while the other end will repel

​Magnets and their uses

• Dynamos and motors

  Doorstopper

  ATM cards

  Junkyards

  Refrigerator doors

​Magnetic field

​•The region of space around a magnet which attracts magnetic materials

•When iron filing are sprinkled around a magnet, the line of force present

•When the lines of force are close together, the magnetic field is strong

•When the lines are further apart, the magnetic field is weak

Magnetic field with iron fillings​

Drawing of magnetic fields

Multiple Choice

Which of the following pairs consists of magnetic materials?

• Iron paper clip and copper coin

• Aluminium can and steel paper clip

• Gold ring and silver bracelet

• Iron paper clip and steel coin

Multiple Choice

Which of the following proves that a piece of metal is already a magnet?

• Copper wire is repelled by it

• A magnet is attracted to it

• Both ends of a compass needle are attracted to it

• One end of a compass needle is repelled by it

Multiple Choice

If the North Pole of a magnet is brought very near to the end of an iron bar, the end of the iron bar and the bar magnet will __________.

• repel each other

• produce an electric spark

• have no effect on each other

• attract each other

Multiple Choice

Aina placed two bar magnets four times next to each other. The movements of the magnets are shown in figure.

What could be concluded by Aina from her observations?

• Like poles attract each other; unlike poles repel each other

• Like poles repel each other; unlike poles attract each other

• Unlike and like poles repel each other

• Unlike and like poles have no effect on each other

Multiple Choice

A bar magnet is broken into three parts X, Y and Z as shown in figure. Which diagram shows the poles in X, Y and Z?