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Exploring Magnets - Magnetic and Non-magnetic Materials

Grade 6CBSE

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

🔑Concepts

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A magnet is a substance that has the property of attracting iron. This property is called magnetism.

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Magnetic Materials: Materials which are attracted towards a magnet are called magnetic materials. Examples include Iron (FeFe), Nickel (NiNi), and Cobalt (CoCo).

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Non-magnetic Materials: Materials which are not attracted towards a magnet are called non-magnetic materials. Examples include wood, plastic, glass, and metals like Aluminum (AlAl) and Copper (CuCu).

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Magnetic Poles: Every magnet has two poles, the North Pole (NN) and the South Pole (SS). The magnetic strength is maximum at these poles.

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A freely suspended magnet always comes to rest in the North-South direction.

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Like poles (N−NN-N or S−SS-S) repel each other, while unlike poles (N−SN-S) attract each other.

📐Formulae

Like Poles  ⟹  Repulsion\text{Like Poles} \implies \text{Repulsion}

Unlike Poles  ⟹  Attraction\text{Unlike Poles} \implies \text{Attraction}

Magnetic Strength at Poles>Magnetic Strength at Center\text{Magnetic Strength at Poles} > \text{Magnetic Strength at Center}

💡Examples

Problem 1:

A student has two bar magnets. If the North pole of the first magnet is brought near the North pole of the second magnet, what will happen? Use the law of magnetism to explain.

Solution:

N↔N  ⟹  RepulsionN \leftrightarrow N \implies \text{Repulsion}

Explanation:

According to the fundamental law of magnetism, like poles repel each other. Since both poles are North (NN), they will push each other away.

Problem 2:

In an experiment, a student counted the number of iron filings sticking to different parts of a bar magnet. They found 4545 filings at the North pole, 4242 at the South pole, and only 33 in the middle. Calculate the total number of filings using vertical addition.

Solution:

4542+390\begin{array}{r} 45 \\ 42 \\ + 3 \\ \hline 90 \end{array}

Explanation:

The total number of iron filings is 9090. This observation confirms that magnetic force is strongest at the poles (45+42=8745 + 42 = 87) compared to the center (33).

Problem 3:

Identify which of the following materials are magnetic: Iron nail, Plastic ruler, Copper wire, Nickel coin.

Solution:

Magnetic: Iron nail, Nickel coin; Non-magnetic: Plastic ruler, Copper wire.

Explanation:

Iron (FeFe) and Nickel (NiNi) are magnetic substances, whereas plastic and copper (CuCu) do not show magnetic properties under normal conditions.