Generation Genius Electric and Magnetic Forces

What are electric and magnetic fields?

• Regions where only electric charges exist

• Places where only magnets can be found

• Areas where objects can push or pull each other without touching

• Zones where no forces act on objects

Answer explanation

Electric and magnetic fields are areas where objects can exert forces on each other without direct contact, allowing for interactions between charged particles and magnets.

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Which metals are commonly attracted by magnets?

• Gold and silver

• Iron, nickel, and cobalt

• Lead and zinc

• Copper and aluminum

Answer explanation

Iron, nickel, and cobalt are ferromagnetic metals, meaning they are strongly attracted to magnets. In contrast, gold, silver, lead, zinc, copper, and aluminum are not magnetic and do not exhibit this property.

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How can you increase the strength of an electromagnet?

• Use a plastic core instead of a metal core

• Add more coils or increase the electric current

• Use a smaller battery

• Decrease the number of wire coils

Answer explanation

To increase the strength of an electromagnet, you can add more coils of wire or increase the electric current flowing through the wire. This enhances the magnetic field produced, making the electromagnet stronger.

What happens when like magnetic poles are near each other?

• They attract each other

• They repel each other

• They create a spark

• They become neutral

Answer explanation

Like magnetic poles, such as two north poles or two south poles, repel each other due to the nature of magnetic forces. This is why the correct answer is that they repel each other.

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What is a compass?

• A gadget that detects sound

• A device that measures temperature

• A tool used to draw circles

• An instrument that contains a magnetized needle pointing north

Answer explanation

A compass is an instrument that contains a magnetized needle which aligns itself with the Earth's magnetic field, pointing north. This makes it essential for navigation, unlike the other options which describe different tools.

How do electric fields differ in strength?

• They are always the same strength

• They only change strength with temperature

• They get weaker as you get closer to the object

• They get stronger as you get closer to the object

Answer explanation

Electric fields get stronger as you approach the charged object due to the inverse square law. This means the force exerted by the field increases as the distance decreases, making the correct choice "They get stronger as you get closer to the object."

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Why can iron filings show a magnetic field?

• They are magnetic themselves

• They are attracted to all metals

• They align along the magnetic field lines

• They change color in a magnetic field

Answer explanation

Iron filings can visualize a magnetic field because they align along the magnetic field lines. This alignment shows the direction and shape of the magnetic field, making it easier to visualize.

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What makes a speaker produce sound?

• The vibration of a permanent magnet alone

• The interaction of a permanent magnet and an electromagnet

• The expansion and contraction of air

• The flow of water through the speaker

Answer explanation

A speaker produces sound through the interaction of a permanent magnet and an electromagnet. This interaction causes the diaphragm to vibrate, creating sound waves in the air.

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What charge do toner particles have in a laser printer?

• Variable

• Negative

• Neutral

• Positive

Answer explanation

Toner particles in a laser printer are negatively charged. This negative charge allows them to be attracted to the positively charged areas of the drum, enabling the printing process to occur effectively.

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Two balloons can repel each other without touching because they (a)  

• They are both filled with helium
• They are both wet
• They are made of metal
• They have the same electric charge

Answer explanation

Balloons can repel each other without touching if they have the same electric charge. Like charges repel due to electrostatic forces, allowing them to push away from each other even at a distance.

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