Electricity and Magnetism

What part of a circuit conducts electricity?

• Wire

• Switch

• Battery

• Light Switch

Answer explanation

The conductor is the wire. It is usually made of copper metal. The wire is the part of a circuit that conducts electricity.

Which part of the circuit can stop the current from flowing?

• Wire

• Switch

• Battery

• Light Bulb

Answer explanation

An open switch will stop the current from flowing. The switch is the part of a circuit that opens and closes to allow the current to flow or stop it.

Which of these would be LEAST useful if one is attempting to create an electromagnet?

• Battery

• Iron Nail

• Distilled Water

• Coil of Copper Wire

Answer explanation

Water would not be needed to create a electromagnet. The copper wire is coiled around the iron bar and then attached to a power source. This creates a magnetic, current-carrying coil of wire called a electromagnet.

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The science class decides to build an electromagnet. They wrap a strand of wire around a large iron nail three times, and connect the wire to a battery. The magnet is strong enough to lift a two pound metal plate.The class wants to be able to lift a four pound plate with the electromagnet. What should they do?

• Wrap an even larger nail in three coils of wire.

• Wrap the nail with wire six times, not three.

• Wrap the nail with only one coil of wire.

• Try using a smaller battery.

Answer explanation

Wrap the nail with wire six times, not three is the correct answer. The strength of an electromagnet is directly related to how many times the wire is coiled around it.

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Magnets and electromagnets can both be used to pick up metal items like iron nails.Even though they are similar, there are differences between magnets and electromagnets.An example of one of these differences is that

• a magnet will pick up items that can't be picked up by an electromagnet.

• an electromagnet will pick up items that can't be picked up by an magnet.

• electromagnets have a set strength, while the strength of a magnet can be adjusted.

• magnets have a set strength, while the strength of an electromagnet can be adjusted.

Answer explanation

magnets have a set strength, while the strength of an electromagnet can be adjusted. A regular magnet is permanent, but the strength of an electromagnet can be adjusted in multiple ways.

What will create static electricity?

• Rubbing a plastic comb on a piece of wool.

• flipping on a light switch in your classroom

• allowing like forces to attract (negative attracts negative)

• wrapping wire around iron and sending a charge through the wire

Answer explanation

Rubbing a plastic comb on a piece of wool will create static electricity.

The wires connecting the switches, lightbulbs, and buzzers must start and end at the power source before the circuit can work. The power source could be a

• battery

• wire

• lightbulb

• switch

Answer explanation

The power source is a battery. The wires connecting all the objects must start and end at the battery.

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Magnets and electromagnets can both be used to pick up metal items like iron nails.Even though they are similar, there are differences between magnets and electromagnets.An example of one of these differences is that

• magnets require an electric current to work.

• electromagnets require an electric current to work.

• magnets will stick to the refrigerator, while electromagnets will not

• electromagnets will stick to your refrigerator, while magnets will not.

Answer explanation

Electromagnets require an electric current to work. A regular magnet is permanent, while an electromagnet needs electricity to work.

Which pair of magnets will ATTRACT each other?

• 
• 
• 
• 

Answer explanation

Image B shows OPPOSITE poles facing each other. Opposites attract; like repel.

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Which diagram represents a complete electric circuit that will make the bulb glow?

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• 
• 
• 

Answer explanation

In a complete electric circuit, the current passes from one end of the battery to the bulb. Then the current flows out from the bulb and back to the other end of the battery. The current must go all around the circuit. Diagram A shows a complete electric circuit.

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