Simple Phenomenon Of Magnets

1. In which pair are both materials magnetic?

Aluminum and Copper

Copper and iron

Iron and steel

Steel and aluminum

Iron and steel are both magnetic materials because they contain iron, which is a ferromagnetic element. Ferromagnetic materials have the ability to retain their magnetization even after the external magnetic field is removed. Aluminum and copper, on the other hand, are not magnetic materials as they do not contain any ferromagnetic elements.

Explanation

Iron and steel are both magnetic materials because they contain iron, which is a ferromagnetic element. Ferromagnetic materials have the ability to retain their magnetization even after the external magnetic field is removed. Aluminum and copper, on the other hand, are not magnetic materials as they do not contain any ferromagnetic elements.

2. Which statement about a magnet is correct?

A magnet attracts a gold rod

Magnet does not attract a plastic rod

A magnet never repels another magnet

Magnet sometimes repels an unmagnetised nickel rod.

A magnet does not attract a plastic rod because plastic is not a material that can be magnetized. Magnets are attracted to materials that have magnetic properties, such as iron or nickel. Plastic is not one of those materials, so a magnet will not be able to attract a plastic rod.

Explanation

A magnet does not attract a plastic rod because plastic is not a material that can be magnetized. Magnets are attracted to materials that have magnetic properties, such as iron or nickel. Plastic is not one of those materials, so a magnet will not be able to attract a plastic rod.

3. Which group contains only non-ferrous metals?

Aluminum, brass and iron

Brass, copper and lead

Copper, Iron and steel

Copper, lead and steel

The group that contains only non-ferrous metals is brass, copper, and lead. Non-ferrous metals are those that do not contain iron. Aluminum and iron are both ferrous metals, so the first option is incorrect. Copper and iron are both present in the third option, so it is also incorrect. The fourth option includes steel, which is an alloy made primarily of iron, so it is also incorrect. Therefore, the correct answer is the second option, which includes only brass, copper, and lead, all of which are non-ferrous metals.

Explanation

The group that contains only non-ferrous metals is brass, copper, and lead. Non-ferrous metals are those that do not contain iron. Aluminum and iron are both ferrous metals, so the first option is incorrect. Copper and iron are both present in the third option, so it is also incorrect. The fourth option includes steel, which is an alloy made primarily of iron, so it is also incorrect. Therefore, the correct answer is the second option, which includes only brass, copper, and lead, all of which are non-ferrous metals.

4. Which metal is suitable to make a permanent magnet?

Aluminum

Brass

Iron

Steel

Steel is suitable to make a permanent magnet because it is a ferromagnetic material. Ferromagnetic materials have strong magnetic properties and can retain their magnetism even after the external magnetic field is removed. Steel is a commonly used material for making permanent magnets due to its high magnetic permeability and ability to retain a strong magnetic field.

Explanation

Steel is suitable to make a permanent magnet because it is a ferromagnetic material. Ferromagnetic materials have strong magnetic properties and can retain their magnetism even after the external magnetic field is removed. Steel is a commonly used material for making permanent magnets due to its high magnetic permeability and ability to retain a strong magnetic field.

5. Permanent magnets are made of _____ materials.

Permanent magnets are made of hard magnetic materials because these materials have a high coercivity, meaning they are able to maintain their magnetization even in the presence of external magnetic fields. This allows them to retain their magnetic properties over a long period of time, hence the term "permanent" magnets. Hard magnetic materials typically have a high magnetic saturation, which means they can generate strong magnetic fields. Examples of hard magnetic materials include alloys such as neodymium-iron-boron (NdFeB) and samarium-cobalt (SmCo).

Explanation

Permanent magnets are made of hard magnetic materials because these materials have a high coercivity, meaning they are able to maintain their magnetization even in the presence of external magnetic fields. This allows them to retain their magnetic properties over a long period of time, hence the term "permanent" magnets. Hard magnetic materials typically have a high magnetic saturation, which means they can generate strong magnetic fields. Examples of hard magnetic materials include alloys such as neodymium-iron-boron (NdFeB) and samarium-cobalt (SmCo).

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