Chapter 19 Magnetism (for final)

When a current-carrying wire is wrapped around an iron core, what can it create?

a magnet

electromagnet

a magnet created by wrapping a current-carrying wire around an iron core

What does a transformer between utility wires and your house do?

decreases voltage

motor

device that transforms electrical energy into kinetic energy

generator

device that uses a magnetic field to turn kinetic energy into electrical energy

transformer

device used to increase or decrease the voltage of an alternating current

alternating current

electric current that changes its direction repeatedly

What is the device shown (page 584 #1)

electric motor

Which energy transformation occurs in an electric motor?

electrical to kinetic

Magnets are used by electric motors in which __________________________________________________________________ generates __________________________________________________________________ that produces Kinetic energy

first blank: a current carrying wire second blank: a magnetic field

Magnets are made from magnetic materials in which Moving electrons in atoms produce _______________________________________________________________ that line up to make _____________________________________________________________

first blank: a magnetic field second blank: a magnetic domain

Magnets are used by generators in which _____________________________________________________ causes A wire loop to rotate that generates ________________________________________________________

first blank: kinetic energy second blank: electric energy

magnetic domain

groups of atoms whose fields pint in the same direction

aurora

light display that occurs when charged particles trapped in the magnetosphere collide with Earth's atmosphere above the poles

What can iron filings be used to show?

magnetic field

What is the region of space affected by Earth's magnetic field called?

magnetosphere

What produces alternating currents?

motors

In which of Earth's layers is Earth's magnetic field generated?

outer core

What will the north poles of two bar magnets do when brought together?

repel

For this transformer (page 582 #15) which of the following describes how the output voltage compares with the input voltage?

smaller

magnetic field

surrounds a magnet and exerts a magnetic force on other magnets

What is the shape of Earth's magnetic field similar to?

that of a bar magnet

How many poles do all magnets have?

two

What are two ways to make the magnetic field of an electromagnet stronger?

1) Increase the number of coils 2) Increase the current

Explain how a doorbell uses an electromagnet by placing the following in order: circuit open, circuit closed, electromagnet turned on, electromagnet turned off, hammer attracted to magnet and strikes bell, and hammer pulled back by a spring.

1. circuit closed 2. electromagnet turned on 3. hammer attracted to magnet and strikes bell 4. circuit open 5. electromagnet turned off 6. hammer pulled back by spring

What is the relationship between a magnet and magnetic domain?

All magnets have magnetic domains.

Why does a magnet attract an iron nail to either of its poles, but attracts another magnet to only one of its poles?

B/c all magnets have a north and south pole, and can only attract one side because the poles will repel; iron is not magnetized (can be a temporary magnet)

Explain why the compass needles are pointed in different directions (pg 585 #9)

Because the needles are aligning with the magnetic field.

What is the relationship that exists between alternating current and direct current?

Both contain moving electrons.

What is the relationship that exists between a motor and a generator?

Both involve conversions between electric and kinetic energy.

What relationship exists between a current and an electromagnet?

By changing the current, the strength and direction of the magnetic field of an electromagnet can be changed.

What relationship exists between the magnetosphere and an aurora?

Charged particles by the sun get deflected to the poles and cause an aurora by the magnetosphere.

Suppose you break a bar magnet in two. How many magnetic poles does each of the pieces have?

Each of the pieces become a tiny magnet, each having a north and south pole.

What prevents most charged particles from the Sun from hitting Earth?

Earth's magnetic field

direct current

Electric current that flows in only one direction

What is the relationship that exists between a generator and a transformer?

Electric generators produce alternating currents (which is an electric current) and transformers are used to increase and decrease the voltage of an electric current.

What will happen to the compass needle when the bar magnet is removed? Explain why this happens.

If the bar magnet is removed, the compass needles will return to magnetic north, and align with Earth's magnetic field.

Two wires carrying electric current in the same direction are side by side and are attracted to each other. Predict how the force between the wire changes if the current in both wires changes direction.

If the current in both wires changes, the force will be as strong. Unlike poles or currents attract.

Suppose you were given two bar magnets. One magnet has the north and south poles labeled, and on the other magnet the magnetic poles are not labeled. Describe how you could use the labeled magnet to identify the poles of the unlabeled magnet.

If you hold the south pole of the labeled magnet to the unlabeled magnet and they repel, this is the south pole; when you hold the north pole to the unlabeled magnet and they repel, this is the north pole.

Explain why a nail containing iron can be magnetized, but a copper penny that contains no iron cannot be magnetized.

Iron has magnetic domains unlike copper.

Explain why the magnetic field produced by an electromagnet becomes stronger when the wire coils are wrapped around an iron core.

It becomes stronger because the magnetic domains line up and becomes a temporary magnet.

What does an electric motor do?

It transforms electrical energy into kinetic energy.

How is an electromagnet different from a permanent magnet?

Its magnetic field can be turned off.

What is the relationship that exists between magnetic force and magnetic field?

Magnetic field is the space where there is a magnetic force.

Explain why auroras are seen mostly near the North Pole and South Pole.

More collisions occur there

Every magnet has a north and a south pole. Where would the poles of a magnet that is in the shape of a disc be located?

On both faces of the disc.

Magnetosphere

Region of space affected by Earth's magnetic field

Why does the needle of a compass point to magnetic north?

The compass needle aligns itself with Earth's magnetic field.

What relationship exists between an electron and magnetism?

The motion of moving electron causes magnetism.

A nail is magnetized by holding the south pole of a magnet against the head of the nail. Does the point of the nail become a north pole or a south pole?

The nail becomes a north pole because opposites attract.

which statement about the domains in a magnetized substance is true?

Their poles point in one direction.