Physics Magnetism Test

What is the most common source of mechanical energy used in commercial power plants?

Running water

Pushing a magnet through an electric field requires work. The greater the electric field,

the stronger the force required to push the magnet through the electric field

A magnetic field around a current-carrying wire forms

Concentric circles around the wire

How are electric and magnetic field waves oriented relative to each other in an electromagnetic wave?

Electric and magnetic field waves are oriented at 90 degree angles relative to each other.

Magnetic fields are produced by

Electric currents

A device that converts electric energy into mechanical energy is a(n)

Electric motor

The magnetism of a piece of magnetized iron can be weakened by

Heating and hammering the iron

What material was used to make the first compass?

Lodestone

How does a compass indicate direction?

A compass aligns with Earth's magnetic field just as iron fillings align with the field of a bar magnet, the N pole of the compass points toward Earth's Geographic North Pole

In an AC generator, the magnitude of the current produced

All of the above (depends on the orientation of the loop in a magnetic field, is zero when the loop is perpendicular to the magnetic field, varies with time)

Magnetic force

All of the above (is a field force, is strongest near a magnet's poles, acts at a distance)

Magnetic fields exist

All of the above (near a magnet, farther away from a magnet, within a magnet)

A compass needle naturally points toward

All of the above (the geographic North Pole, the S pole of a magnet, Earth's North Magnetic Pole)

Where is Earth's magnetic N pole located?

Antarctica

When a wire is moving perpendicular to a magnetic field, the force on the charges is

At a maximum

A transformer changes

Both the amperage and the voltage of an electric current

In addition to running water, what are there other sources of mechanical energy used by generators to generate electrical energy?

Burning coal, nuclear fission, wind, hot water from geysers (geothermal), or solar power.

Where are Earth's magnetic poles located?

Canada and Antarctica

When an iron rod is inserted into a solenoid's center, the magnetic field produced by the current in the loops

Causes alignment of the domains in the iron

A current-carrying wire is perpendicular to the surface of a table. The direction of current is toward the floor. What is the direction of the magnetic field as viewed from above?

Clockwise

What instrument is used to trace the direction of a magnetic field

Compass

The magnetic field strength of a magnet

Decreases as distance from the magnet increases

Light travels as

Electromagnetic waves

A potential difference causes

Electrons to move from the negative terminal to the positive terminal of a battery.

What do galvanometers use to measure the current in a circuit?

Galvanometers measure the current in a circuit using the magnetic field produced by the curent in a coil

How are generators different from electric motors?

Generators convert mechanical energy to electrical energy, whereas electric motors convert electric energy to mechanical energy

What causes the magnetic properties of bar magnets?

In the material that a bar magnet is composed of, the magnetic fields of the electrons do not all cancel, so each atom has its own magnetic field. The domains in the bar magnet are aligned more in a common direction.

Transforms can

Increase or decrease voltage

What are two ways to increase the strength of the magnetic field of a solenoid?

Increasing the current or inserting an iron core would increasing the magnetic field strength of a solenoid

The strength of a magnetic field of a solenoid can be increased by

Increasing the number of loops on the solenoid

The strength of the magnetic field of a solenoid can be increased by

Inserting an iron rod

How can the magnetic field around a permanent magnet be determined?

It can be determined with a compass. The direction of the magnetic field is defined as the direction in which the north pole of a compass needle points at that location

In a magnetized substance, the domains

Line up more uniformly in one direction

Magnetically soft substances

Lose their magnetism more easily than others

What do magnetic field lines that are close together indicate?

Magnetic field lines that are close together indicate a strong magnetic field

Where is Earth's magnetic S pole located?

Northeastern Canada

Both electric and magnetic fields in an electromagnetic wave are

Perpendicular to the direction that the wave travels

Which orientation characterizes the magnetic domains in an unmagnetized piece of iron?

Random

Like magnetic poles always

Repel each other

What causes a compass needle to point to geographic north?

The compass needle aligns with Earth's magnetic field.

In an AC generator, when charges experience the most rapid change in magnetic force,

The current increases

Describe the orientation of the domains inside an unmagnetized piece of iron.

The domains are randomly oriented in an unmagnetized piece of iron.

What is the relationship between the electric field and the magnetic field in an electromagnetic wave?

The electric and magnetic fields are perpendicular to each other and to the direction the EM wave travels. As the wave moves along, the changing electric and magnetic fields regenerate each other.

What is the relationship between the current in an electromagnet and its magnetic field?

The greater the current, the stronger its magnetic field.

If the head of an iron nail touches a magnet, the nail will be magnetized. If the nail touches the north pole of the magnet, what kind of pole is at the point of the nail? Explain.

The head of the magnetized nail, which is touching the north pole of the magnet, will be a south pole. Otherwise, it would be repelled by the magnet. The tip of the nail will be a north pole.

How does inserting an iron rod through the center of a solenoid increase the strength of its magnetic field?

The magnetic field of the rod adds to the coil's field, creating a stronger magnet than the solenoid alone.

A bar magnet is suspended and allowed to rotate freely. If the magnetic field of Earth is considered to be equivalent to that of a large bar magnet, which pole of the suspended magnet would point toward the Geographic North Pole of Earth?

The north (N) pole would point to the Geographic North Pole of the Earth

What determines the strength of the magnetic field?

The strength of the magnetic field depends on the material from which the magnet is made and the degree to which it is magnetized

A solenoid is standing on its end on a table. The direction of current is counterclockwise. Which end of the solenoid is a N pole?

The top

An electric motor and a generator are similar in that both

Transform energy into a different form

An example of a naturally occurring magnetic rock is a

lodestone

When a wire is moving parallel to a magnetic field,

no current is induced in the wire

The north pole of one magnet will be attracted to

the middle of a magnet

When a charge moves along or opposite the direction of the magnetic field lines, the magnetic force is

zero

What is a galvanometer?

A galvanometer is an instrument that measures the amount of current in a circuit.

What is a generator?

A generator is a device that uses electromagnetic induction to convert mechanical energy to electric energy.

What is a magnetic pole?

A magnetic pole is an area of a magnet where the magnetic force appears to be the strongest

What is a solenoid

A solenoid is a long, wound coil of insulated wire.

What is a transformer?

A transformer is a device that can change one alternating current voltage to a different alternating current voltage.

Generators convert

Mechanical energy to electrical energy

The strength of a magnetic field created by current in a wire can be increased by

Wrapping the wire into a coil