Magnetism and Electromagnetism Review

Magnetism Review

By

• it is a force of attraction or repulsion due to the motion of the electrons

  • refers to the properties of magnets and their interactions

What is magnetism?​

Electromagnet

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil.

electric ------> magnet

these are at the ends of a magnet and are where the magnetic field is the strongest.

• because of this when suspended on a string a magnets will position itself to have the strong ends poin​ting north or south (hence why they are labeled N and S on a magnet)

Magnetic Poles

Electromagnet is a temporary magnet.

The temporary means the magnet field will appear, if a current flows through the coil.

Multiple Choice

What is an electromagnet?

• a temporary magnet made from current carrying wire around a magnetic metal core.
• a permanent magnet with a north and south pole

• this is the force that acts between bodies of like electric charge, causing them to separate.

  • like poles of a magnet will repel (push away from) each other because of this property

Repulsion

Multiple Choice

How are electromagnets different from magnets?

• magnets have a North and South pole

• you can turn an electromagnet on/off

• magnets are more powerful

• the force that acts between oppositely charged bodies, causing them to draw together.

  • opposite poles of a magnet will attract (come together) because of this​ property

Attraction

Electromagnet components

Battery provides the energy or the power source to run the electromagnet.

The wire provides the pathway to carry electricity from component to component.

The magnetic material core becomes a temporary magnet when electricity is flowing through the circuit.

Multiple Choice

which of the following situations represents an attractive forces between two poles?

• the north end of one magnet pointing to the north end of another magnet

• the north end of one magnet pointing to the south end of another magnet

• the south end of a small magnet pointing to the south end of a large magnet

Multiple Choice

Which component provides the energy or the power source to run the electromagnet?

• Iron nail

• wire

• Switch

• Battery

Multiple Choice

The strongest parts of the magnet are ...

• fronts

• backs

• poles

• middle

Multiple Choice

What component provides the pathway to carry electricity from component to component?

• battery

• wire

• switch

• iron nail

Multiple Choice

The area around a magnet is called the .....

• attraction zone

• work area

• magnetic field

• hot zone

Multiple Choice

What component becomes a temporary magnet when electricity is flowing through the circuit?

• iron nail

• copper wire

• battery

• switch

Multiple Choice

A north pole and a south pole will attract.

• True
• False

Electromagnet

The magnetic field will stronger if:

The electric current increase.

The number of turn of coil increase.

The magnetic field of electromagnet is also depend on the core.

If we put the iron (magnetic material) inside the core the electromagnet will stonger than we left the core with only the air.

• region around a magnet that is affected by the magnet.

  • Strongest at the poles

  • the force forms lines that go out of (away from) the North Pole and wrap back around to go in at (towards) the South Pole.

Magnetic Field

Multiple Choice

What would increase the strength of an electromagnet?

• Increasing the amount of current flowing through the wire.
• Inserting a wooden core inside the coil
• Changing the direction of the current
• Decreasing the number of coils of wire

How are magnetic field and magnetic force related?

Magnetic force increases as the magnetic field becomes stronger.

• so stronger magnets have stronger magnetic fields​

Using the Right-Hand Rule 

The tumb will show North direction while the other fingers show current direction.

Magnetic Field

• can be represented by lines of force called magnetic field lines

• ​the closer the magnetic field lines are, the stronger the magnetic field is at that point.

  • they are closer together near the magnet​

Electromagnetic Waves

Electricity and Magnetism have a great effect on each other because they are a part of the same wave.

Magnetic Field

• lines always go from north to south

• lines connecting poles show attraction​

• lines that move away from poles show repulsion​

Electric generator

 The electric generator is a device that converts mechanical energy into electrical energy.

magnet ---> electric

First phenomena founded by Micheal Faraday

Multiple Choice

What is being shown by the magnetic force field lines shown below?

• Attractive force by like poles

• Attractive force by opposite poles

• Repulsive force by like poles

• Repulsive force by opposite poles

Multiple Choice

What is the device which converts mechanical energy to electrical energy?

• electric generator

• electric motor

Multiple Choice

Are the magnetic field lines in the picture correct?

• Yes, because they point from north to south.
• No, because they point from north to south (they're supposed to go the other way).
• Yes, because the North pole is on the left in all pictures.
• No, because the North pole is on the left in all pictures (it's supposed to be on the right).

Faraday experiment

By moving a magnet into a coil of wire, electricity is produced in the wire. This can produce an alternating current (AC)

Multiple Choice

What is being shown by the magnetic force field lines shown below?

• Attractive force by like poles

• Attractive force by opposite poles

• Repulsive force by like poles

• Repulsive force by opposite poles

Do magnets attract ALL metal objects?

Multiple Choice

According to the experiment, if we replace the coil with greater number of turn, ____

• The current will be greater

• The current will be weaker

​NO, there are a few magnetic materials.

Magnets do not attract all metal materials

• ​examples of metals it will not attract:

  • pieces of aluminum foil or gold

• ​examples of metals it will attract:

  • ​iron, cobalt, and nickel

    • these can be made into permanent magnets

    • these are magnetic because they have electron magnetic properties that do not cancel out and so each will behave like a small magnet with its own magnetic field and poles

Electric generator

• We can produce the electricity by rotating electric conductor between two magnets.

• The electricity will greater if :

  • we replace the stronger magnet.
  • we rotate the conductor in faster rotation.

  
  

​Magnetic Domain

unmagnetized magnetized

Multiple Choice

Huge wheels that rotate when pushed by water, wind or steam.

• turbines
• leads
• magnets

Multiple Choice

Which one of the metal materials will a magnet not pick up?

• Cobalt

• Iron

• Aluminum

Electric Motor

• We can produce motion by running electricity through a coil of water near a magnet.

​

Electrical Energy -> Mechanical Energy​

Multiple Choice

You know this substance is magnetized because

• all the domains have right angles
• the arrows are drawn in red
• the domains are aligned
• the domains are random

Multiple Choice

These magnetic domains are:

• strongly magnetized

• slightly magnetized

• unmagnetized

Multiple Choice

Electric motors are devices that convert _____ energy into  _____ energy.

• electrical; mechanical
• mechanical; electrical
• chemical; potential
• mechanical; kinetic

• Earth is thought to have a nickel iron core that gives it a magnetic field similar to a bar magnet.​

The earth is kind of like a giant magnet.​

Transformers

• used ton increase or decrease voltage

• used to decrease voltage before it enters your home or delicate electronics

Multiple Choice

Why does a compass needle point north?

• The compass is a bar magnet
• Because north is up
• Because it's magic
• It lines up with the Earth's magnetic field

​https://www.youtube.com/watch?v=agujzHdvtjc

Multiple Choice

A compass is basically a magnet that can spin. Which end of the compass points toward Earth's geographic north pole?

• south pole

• north pole

• the pointy end

• the flat end

Multiple Choice

If a transformer reduces voltage, it is called a....................... transformer.

• step left

• step right

• step up

• step down

• the magnetic field that is inside of the magnet is strong enough to prevent the constant motion of atoms in the magnetic domains from bumping the domain out of alignment.

Permanent Magnet​s

Review

Multiple Choice

Using the right hand grip rule, A represents the direction of the

• current

• magnetic field

• when a magnetic material is close to a magnet it becomes a magnet.

• when a weak magnet is brought near a strong magnet the weak magnet will align with the strong.

Induced Magnet​s

Multiple Choice

What is formed when a wire in an electric circuit is wrapped around an iron core producing a magnetic field?

• electromagnet
• generator
• magnet
• electric motor

• produced when a moving charge creates a magnetic field

• when charged particles are in motion, a magnetic force field (one that is perpendicular to the motion of the particles) is created

Electromagnets

Multiple Choice

Used at powerplants to produces elecrical energy for our homes.

• generator
• electric motor
• electromagnet

Multiple Choice

Once a paperclip touches a magnet and becomes a magnet itself, does a paperclip STAY that way? Or does it stop being a magnet?

• stay that way forever

• stop being a magnet

• stay that way for a short time

Multiple Choice

Produces an electric current when a coil of wire wrapped around an iron core is rotated near a magnet.

• generator
• electric motor
• electromagnet

Multiple Choice

A magnet must always have two poles, even if cut in half, because

• A magnet is made up of tiny magnetic domains that are aligned.

• Each pole divides in half and the magnetic field becomes weaker.

• Magnetic domains are out of alignment.

Multiple Choice

This picture is an example of a ________________.

• Motor

• Generator

• Step-up transformer

• Step-down transformer

Multiple Choice

What causes the magnetic field to form in an electromagnet?

• Electromagnets are only called magnets because electricity is involved.

• The domains of the magnet become aligned

• The magnetic field is absorbed from another magnet

• Electric current flowing in a wire

Multiple Choice

a generator converts:

• Mechanical energy to electrical energy

• Electrical energy to mechanical energy

• Heat energy to mechanical energy

• Chemical energy to electrical energy

Multiple Choice

An electromagnet differs from a permanent magnet because

• permanent magnets require an electrical current to produce a field.

• electromagnets can be turned off or weakened by reducing to stopping the flow of current.

• electromagnets only have one pole, while permanent magnets always have two.

• permanent magnets require the movement of electrons, while electromagnets do not.