Electromagnets

Which material can be magnetized?

• Plastic

• Iron

• Aluminum

• Wood

Answer explanation

Iron is a ferromagnetic material, meaning it can be easily magnetized. In contrast, plastic, aluminum, and wood are not magnetizable under normal conditions.

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NGSS.MS-PS2-3

What happens to a compass needle when you connect a wire to a battery?

• It stays the same

• It points north

• It moves because of the magnetic field

• It disappears

Answer explanation

When a wire is connected to a battery, it creates an electric current that generates a magnetic field. This magnetic field can influence the compass needle, causing it to move and point in the direction of the magnetic field.

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Why does thicker wire make a stronger electromagnet?

• It lets more electricity flow through

• It has less magnetism

• It holds less energy

• It doesn't matter

Answer explanation

Thicker wire allows more electricity to flow through it due to its lower resistance. This increased current enhances the magnetic field strength, making the electromagnet stronger.

Why does thicker wire make a stronger electromagnet?

• It lets more electricity flow through

• It has less magnetism

• It holds less energy

• It doesn’t matter

Answer explanation

Thicker wire allows more electricity to flow through it due to its lower resistance. This increased current enhances the magnetic field strength, making the electromagnet stronger.

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NGSS.MS-PS2-3

Which of these statements is true about electromagnets?

• All metals can be magnetized

• Only iron and steel can be magnetized

• Plastic is a good material for electromagnets

• Electromagnets don’t need electricity

Answer explanation

Only iron and steel can be magnetized due to their ferromagnetic properties, allowing them to become permanent magnets. Other metals do not exhibit this behavior, making this statement true.

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NGSS.MS-PS2-3

What is one thing that makes a telephone better than a telegraph?

• You can send messages without wires

• You can send more than one message at a time

• You don’t need electricity

• It uses a secret code

Answer explanation

The telephone allows for simultaneous communication, enabling multiple messages to be sent at once, unlike the telegraph, which transmits one message at a time. This makes the telephone more efficient for communication.

More winds of wire makes a weaker electromagnet.

• True

• False

Answer explanation

The statement is false. More winds of wire actually strengthen an electromagnet by increasing the magnetic field produced, as each loop of wire contributes to the overall magnetic effect.

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NGSS.MS-PS2-3

Iron is a material that can be magnetized.

• True

• False

Answer explanation

Iron can be magnetized because it is a ferromagnetic material. This means it can be influenced by a magnetic field and can retain magnetization, making the statement true.

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NGSS.MS-PS2-3

Electricity creates a magnetic field around a wire.

• True

• False

Answer explanation

True. When an electric current flows through a wire, it generates a magnetic field around it, as described by Ampère's circuital law. This phenomenon is fundamental to electromagnetism.

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The material that works best as a core for an electromagnet is

• Iron

• Plastic

• Aluminum

• Wood

Answer explanation

Iron is the best core material for an electromagnet because it is ferromagnetic, allowing it to enhance the magnetic field significantly. Other materials like plastic, aluminum, and wood do not have the same magnetic properties.

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NGSS.MS-PS2-3

NGSS.MS-PS2-5