Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A magnet is a material that exerts a force of attraction on magnetic substances like Iron (), Cobalt (), and Nickel ().
Natural magnets are found in nature, such as Magnetite (Lodestone), which has the chemical composition .
Every magnet has two poles: the North Pole () and the South Pole (). The magnetic strength is maximum at these poles.
The directive property states that a freely suspended magnet always aligns itself in the geographic North-South direction.
Magnetic poles always exist in pairs. Even if a magnet is broken into smaller pieces, each piece will have its own and poles; magnetic monopoles do not exist.
The Law of Magnetism: Like poles repel each other ( or ), and unlike poles attract each other ().
Magnetic Induction is the phenomenon where a non-magnetic material (like a soft iron bar) acquires magnetic properties temporarily when placed near a strong magnet.
📐Formulae
💡Examples
Problem 1:
A student breaks a bar magnet into smaller pieces. How many North poles and South poles will be present in total?
Solution:
There will be North poles and South poles (Total poles).
Explanation:
According to the property that poles always exist in pairs, each piece becomes a complete magnet with one pole and one pole. Therefore, poles.
Problem 2:
Why does a magnetic compass needle always point in the North-South direction?
Solution:
This is due to the directive property of magnets and the Earth's magnetic field.
Explanation:
The Earth behaves like a giant bar magnet with its magnetic poles near the geographic poles. The pole of the compass needle is attracted to the Earth's magnetic south pole (located near geographic North), causing it to align .
Problem 3:
If two magnets are placed such that their North poles are facing each other, what force will be observed?
Solution:
A force of repulsion ().
Explanation:
By the Law of Magnetism, like poles ( and ) repel each other.