Review Electricity and Magnetism

A student is creating an electromagnet for an investigation. Which feature of the electromagnet will least influence the magnetic force?

• the material of the core

• the brand of the battery

• the number of wire coils

• the size of the power source

Which of the following might make the spoons repel each other?

• A and B are not charged at all

• Both A and B are the same charge (negative and negative)

• A and B are opposite charges (A is positive and B is negative)

Which statement best describes why the child's hair stands up after he slides down the slide?

• Energy was transferred from the slide to the child through induction, causing the child's hair to become charged and stand up.

• Friction caused a transfer of electrons between the slide and the child, making each of his like-charged hairs repel each other

• Energy was transferred from the child to the slide through conduction, causing the child's hair to become charged and stand up.

• Friction caused a transfer of electrons between the slide and the child, making his like-charged hairs attract the air through induction.

Which combination of materials would allow Darwin to make the strongest electromagnet?

• iron nail, copper wire, 5-volt battery

• iron nail, copper wire, 1.5-volt battery

• wooden pencil, copper wire, 5-volt battery

• wooden pencil, copper wire, 1.5-volt battery

What conclusion can Brian most likely draw about his observation?

• The two paper clips were outside the magnet's electromagnetic field.

• The two paper clips did not have magnetic properties like the others.

• The two paper clips were not light enough to be pulled by the magnet.

• The two paper clips were repelled by the electromagnet and not picked up

What must an object gain or lose to become electrically charged?

• protons

• electrons

• neutrons

• nucleus

What is the difference between charging by conduction and charging by induction?

• During conduction, charges move between objects that briefly touch; during induction, charges move between objects that are rubbed together.

• During induction, charges move between objects that briefly touch; during conduction, charges move between objects that are rubbed together.

• During conduction, charges move between touching objects; during induction, charges are rearranged within an object that is near another object.

• During induction, charges move between touching objects; during conduction, charges are rearranged within an object that is near another object.

Groups of atoms that align to form small, magnetized regions in a material are

• geographic domains

• magnetic field lines

• magnetic domains

• magnetic poles

Catherine rubs an iron nail with a ferromagnet (permanent) in one direction. Which of the following is true of the magnetized nail?

• It will only be attracted to the north pole of a bar magnet.

• It has a strong north pole and a much weaker south pole.

• Its domains have become rearranged so that they line up in the same direction.

• The bar magnet has caused a random arrangement of the nail’s domains.

Electrical wires sometimes have a plastic coating wrapped around them. How does this make the wires safer to handle?

• Plastic does not react chemically with air.

• Plastic is smooth and not easily frayed.

• Plastic is a good insulator.

• Plastic will melt if the wires overheat