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Physics - Magnetism: Magnetic materials and poles

Grade 4IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Magnets have two ends called poles: the North pole (NN) and the South pole (SS).

Magnetic materials are materials attracted to a magnet. The four main magnetic metals are Iron (FeFe), Steel (an alloy of iron), Nickel (NiNi), and Cobalt (CoCo).

Non-magnetic materials, such as Aluminum (AlAl), Copper (CuCu), gold, plastic, and wood, are not attracted to magnets.

The Law of Magnetism: Like poles repel each other (NN and NN or SS and SS push away), while opposite poles attract each other (NN and SS pull together).

Magnetism is a non-contact force, meaning magnets do not have to touch an object to exert a force on it.

A magnetic field is the region around a magnet where the magnetic force can be detected.

📐Formulae

Like Poles=Repulsion(NN)\text{Like Poles} = \text{Repulsion} (\leftarrow N \quad N \rightarrow)

Opposite Poles=Attraction(NS)\text{Opposite Poles} = \text{Attraction} (\rightarrow N \quad S \leftarrow)

💡Examples

Problem 1:

A student has two bar magnets. If they point the South pole (SS) of the first magnet toward the North pole (NN) of the second magnet, what will happen?

Solution:

The magnets will move toward each other due to attraction.

Explanation:

In magnetism, opposite poles (SS and NN) create an attractive force that pulls the objects together.

Problem 2:

Which of the following items will be attracted to a magnet: a copper penny (CuCu), an iron nail (FeFe), or a plastic ruler?

Solution:

The iron nail (FeFe).

Explanation:

Iron is a magnetic material, whereas copper and plastic are non-magnetic and do not experience a force from the magnet.

Problem 3:

If you snap a bar magnet in half, how many North (NN) poles and South (SS) poles will you have in total?

Solution:

Two North (NN) poles and two South (SS) poles.

Explanation:

Every magnet, no matter how small, must have both a North and a South pole. Breaking one magnet creates two smaller, complete magnets.