8.4.2-Making Magnets w/ an Electric Current

​Why do Magnets attract things?

The magnetic field is the area around a magnet that has a magnetic force.

​

There is a magnetic field line that show two things:

1. The lines show the direction of the field (will sometimes have an arrow)

2. Where the lines are the closest together is where the field is the strongest. ​

​Draw Activity!

Use a whiteboard and your peers to draw pictures of the following! Use the information I just gave you to help you with the drawing!

​

A. Draw a picture of two magnets that are repelling each other.

B. Draw a picture of magnets that re attracting to each other. ​

Subject | Subject

Some text here about the topic of discussion

​Were you on the right track? Thumbs up or Thumbs down!

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

Remember this​!

The Magnetic field always comes out of the north pole to the south pole.​

​

97

Magnetic Poles

Every magnet has 2 poles ­ North and South
It's similar to the charge being either positive or negative

98

Forces between Magnetic Poles

Opposite magnetic poles attract.

Like magnetic poles repel.

Click here to launch a video
on magnetic levitation

99

The Compass

A compass is just a bar magnet that is free to swing about.
The compass needle is attracted to Earth's magnetic poles.

The compass is an indicator of
Earth's magnetic field.

100

Earth's Geographic
North Pole is actually a
Magnetic South Pole!

A compass' true North Pole is attracted to Earth's Geographic North Pole
(Magnetic South Pole), and vice versa.

Geographic and Magnetic Poles

Earth's Geographic
South Pole is actually a
Magnetic North Pole!

101

Magnetic Field Line Drawings

Forces around magnets can be visualized by "lines of force"
These lines indicate the strength of a magnetic field.

Where have we seen force lines like this before?

*sketch this

in the space provided

*note that arrows enter

South and exit North

102

3 Magnetic Field Line Rules

Lines exit North Poles and enter South Poles

Closer lines equal stronger force

Field lines never cross!

103

As we move away from a
magnetic pole, What
happens to the strength of
the magnetic field?

A

B

Compare the spacing of the field lines
at A vs. B

What do you notice?

Magnetic Field
Drawings

it gets more spread out which

means the magnetic force is
weaker

104

Visualizing Magnetic Fields

By sprinkling iron filings around a magnet, we see that they will line up
differently depending on the magnetic field of the magnet.

lines connect in middle so this is attraction

lines repel upward/downward

Multiple Choice

33 This photo depicts magnets which could be aligned _______________.

• North-North

• North-South

105

33 This photo depicts magnets which could be aligned _______________.

A North North

B North South

Answer

*not in notes but good extra practice*

repelling so must be same poles

Multiple Choice

33 This photo depicts magnets which could be aligned _______________.

• North-North

• North-South

106

34 This photo depicts magnets which could be aligned _______________.

A North North

B North South

Answer

*not in notes but good extra practice*

attracting so must be opposite poles

107

Magnetic Fields Lines

Can you visualize
the photos you
just saw with
these drawings?

108

Attractive force between unlike poles

This magnetic field line diagram shows an attractive force between
unlike poles.

109

Repulsive force between like poles

This magnetic field line diagram shows a repulsive force between
like poles.

south/south will

look exactly the
same but arrows
ENTER south

Multiple Choice

35 Like magnetic poles:

• attract

• repel

Multiple Choice

36 This type of field drawing represents:

• attraction

• repulsion

• suspension

112

36 This type of field drawing represents:

A

attraction

B

repulsion

C

suspension

Answer

Multiple Choice

39 Magnetic Field lines exit from the south pole of a magnet.

• True

• False

115

39 Magnetic Field lines exit from the south pole of a
magnet.

True

False

Answer

Multiple Choice

40 As distance is increased away from a magnetic field source, the magnetic field intensity will ___________.

• Increase

• Decrease

• Stay the same

116

40 As distance is increased away from a
magnetic field source, the magnetic
field intensity will ___________.

A

Increase

B

Decrease

C

Stay the same

Answer

inversely/indirectly proportional

119

Electrical Current and Magnetic Fields

In this diagram, the red lines circling the wire are the magnetic field lines!

An electrical current (moving charge)
placed through a wire produces a magnetic
field around the wire!

120

The greater the electrical current, the greater the strength
of the magnetic field produced.

The magnitude of magnetic field produced by a straight
current­carrying wire at a given point is:

• Directly proportional to the current passing in the wire.

• Inversely proportional to the distance of that point from the
wire.

Electrical Current and Magnetic Fields

122

Visualizing Magnetic Fields in the Lab

By sprinkling iron
filings around a
magnet, we see that
they will line up with
the magnetic field of
the magnet.

126

The Left Hand Rule

For a COIL, use the LEFT HAND RULE.
­ When the fingers point in the direction of the current in the loops, your
thumb points in the North direction of the magnetic field

Click for a video on the Left Hand Rule

Left Hand Rule -

*helpful reminder - it works the same as the right hand rule

except Left hand rule is used when a coiL is present (both have a L)

How are Electric Currents & Magnetic Fields Related?

• Magnets and Electricity share several elements

  • Both create fields around an object

  • Both follow similar rules

    • Opposites attract, Same Repel

• From the similarities, it is possible to show a relationship between the two

Multiple Choice

An Electric ___________ produces a magnetic field.

• Charge

• Discharge

• Current

• Spark

What is the Magnetic Field Produced by a Current Like?

• The Magnetic Field produced by a current has strength and direction

• The Current can be turned on or off and change the magnetic field

  • When a field is turned on or off, the strength changes and the direction reverses

Changing the Strength of a magnetic field

• There are two ways a person can change the strength of a magnetic field

  • Increase the amount of current in the wire

  • Add Loops to the wire

    • When the wire is looped, the magnetic field lines a brought closer together and made stronger

      • Every additional loop strengthens the magnetic field

Currents that Generate Electromagnetic Fields

• There are two types of currents that can generate an electromagnetic field

  • Solenoids

  • Electromagnets

Solenoids

• Solenoid: A Coil of Wire with a current

  • The two ends act like the poles of a magnet

    • Poles can change if the direction of the current changes

Electromagnets

• Electromagnet: A solenoid with a strong magnetic material on the inside

  • Both the current of the wire and the magnetized core produce magnetic fields, making the magnetic attraction much stronger

  • Can be turned on and off with the current

• Electromagnets are used in many different objects

  • From small electronics to large industrial tools

Increasing the Strength of Electromagnets

• There are four ways to increase the strength of an Electromagnet

  • Increase the Current in the Solenoid

  • Add more Loops to the Wire

  • Wind the Coils of the Solenoid closer together

  • Use a material that is more magnetic in the core

Multiple Choice

How can you increase the strength of an electromagnet?

• Moving a compass close to the electromagnet

• Adjusting the magnetic declination

• Using a stronger magnetic material for the core

• Reversing the magnetic Domains

Multiple Choice

Both solenoids and electromagnets produce magnetic fields using

• electric currents and coiled wires

• compasses and magnetic fields

• coiled wires and a ferromagnetic core

• electric current and a battery

Multiple Select

A magnetic field produced by a current has what two things?

• Strength

• Direction

• Charge

• Static

Multiple Choice

What is being represented in the picture?

• An Electromagnet

• Static Discharge

• A Solenoid

• A Compass

Multiple Choice

A force that can act at a distance is called

• non contact force

• friction

• balanced

Multiple Choice

Electric current can flow through a wire only if it forms a ____

• Open Loop

• Closed Loop

Multiple Choice

All electric charge is based on the ___________ in atoms.

• Protons and Electrons

• Protons and Neutrons

• Neutrons and Protons

• Neutrons and Electrons

Multiple Choice

The strength of an electric force depends on the ___________ of electric charge on the particles and the ______________ between them.

• Amount; distance

• Size; distance

• Type; attraction

Multiple Choice

All magnets have 2

• fields
• colors
• poles
• all of the above

Multiple Choice

What does magnets repelling mean?

• Magnets move away from each other

• Magnets do not have magnetism

• Magnets move towards each other

Multiple Choice

_{^{The magnet's shown will}}

• not move
• attract
• repel
• all of the above

Multiple Choice

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

• attraction zone

• work area

• magnetic field

• hot zone

Multiple Choice

Earth's magnetic South Pole is near Earth's geographic North Pole

• true

• false

Multiple Choice

Earth has a magnetic field that is similar to a bar magnet's magnetic field.

• true

• false

Multiple Choice

What do we know about Earth's Magnetic Field?

• It is likely caused my the molten iron core of the Earth.

• It protects us from solar winds.

• It causes the auroras.

• It does not deflect particles that move parallel to the field lines.

• all of the above.

Multiple Choice

Electromagnetism is a magnetism produced by an electric current.

• True

• False

Electromagnets

How are they made and how can they be made stronger?

Multiple Choice

Bob made an electromagnet but it was very weak.  How can he make it stronger?

• take away a d-cell
• wrap the wire loosely
• use thicker wire
• use less winds

Multiple Choice

How are electromagnets different from magnets?

• magnets can be turned on/off
• you can turn an electromagnet on/off
• magnets are more powerful
• magnets have a North and South pole

Multiple Choice

What device is made of coils of wire with an electrical current passing through it in order to generate a magnetic field?  

• Electromagnet 
• Generator
• Electron Magnet 
• Motor

Multiple Choice

An electric current produces

• a magnetic field.

• an electromagnet.

• a solenoid.

• an insulator.

Multiple Choice

Increasing the number of coils in an electromagnet will _________ the strength of the magnet.

• decrease

• increase

• not affect

Multiple Select

Permanent Magnets and Electromagnets are similar in which TWO ways?

• it can be turned off and on

• they both have a north and south pole

• they are surrounded by a magnetic field

Multiple Choice

Electromagnets are useful in industry such as a junk yard because they

• have strong north and south poles

• are easy to lift

• can be turned off and on

Multiple Select

What THREE ways are electromagnets different from permanent magnets?

• they can be turned off and on

• they can increase in strength by increasing the current in the wire

• they are smaller in size

• they can change which is the north and south pole

Multiple Choice

The electromagnetic forces from a current carrying wire are strong enough to move the compass needle. The forces can be made stronger by

• making the wire shorter

• making the wire longer

• making the wire into loops

Multiple Choice

Electronic devices create magnetic fields because they

• are magnets

• are compasses

• have moving particles with electric charge

Multiple Choice

Electronic devices create magnetic fields because they

• are magnets

• are compasses

• have moving particles with electric charge

Multiple Choice

What two forces are required for generators and electric motors to work?

• magnetism and thermal

• electricity and magnetism

• electricity and thermal

• magnetism and radiant

1. Using a stronger/bigger magnet

2. ​Moving the magnetic field faster

3. More windings/loops in the coil

​

Induced voltage can be increased by...

Generators: Mechanical Energy Electrical Energy

• Mechanical energy is used to turn a rotor attached to an armature (coil)

• The armature is in a magnetic field

• As the wire is turned, it experiences a changing magnetic field

• This results in a voltage and current

• Input: Electrical energy (battery)

• Output: Mechanical energy (coil turns)

• Motor parts: battery

Motors only

• ​Input: Mechanical energy (turn the coil)

• Output: Electrical energy (voltage and current)

• Motor parts: device to be powered

​​Generators only

Parts:

Magnet

Armature

Both

Multiple Choice

Generators are devices that convert _____ energy into _____ energy.

• chemical; mechanical

• mechanical; electrical

• electrical; mechanical

• potential; kinetic

Multiple Choice

What device is made of coils of wire with an electrical current passing through it in order to generate a magnetic field?  

• Electromagnet 

• Generator

• Electron Magnet 

• Motor

Multiple Choice

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

• electrical; mechanical

• mechanical; electrical

• chemical; potential

• mechanical; kinetic

Multiple Choice

What two forces are required for generators and electric motors to work?

• magnetism and thermal

• electricity and thermal

• electricity and magnetism

• magnetism and radiant

Multiple Choice

How could the experimenter increase the amount of electricity being induced by this experiment?

• Increase the number of coils

• Decrease the number of coils

• Flip the magnet around

• Nothing, the amount of electricity cannot be increased

Multiple Select

Select all of the materials that make good insulators.

• rubber

• steel

• copper

• wood

• plastic

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. An electromagnet is a temporary magnet (easy to magnetize, easy to demangetize)

What is an electromagnet?

Multiple Choice

How can you make an electromagnet stronger?

• Use a smaller battery

• Put it next to a compass

• Increase the number of coils around the nail

• Move it further away from ferromagnetic materials

Multiple Choice

Where on a magnetic field is the force the strongest?

• At the north pole

• In the middle

• On both poles

• On the bottom

An electric motor converts electricity into mechanical energy, providing a power source for machinery.

​

Examples: Refrigerator, Hair Dryer, Vacuum Cleaner, Power Tools, etc.

Electric Motor

​

​A generator does the opposite of this, converting mechanical energy into electricity.

​

Backup Generators are used when there is no electricity and you still need power.​

Generator

​

Multiple Choice

What is the difference between an electric motor and a generator?

• Generators convert mechanical energy to electrical energy

• Electric motors convert mechanical energy to electrical energy

• They do the same thing, but they are built different

• They do the same thing in with different types of currents

The commutator causes the current in the electromagnet to change direction, which reverses the poles of the electromagnet. The magnets now repel each other and the motor keeps rotating.​

​

Parts of an electric motor

Multiple Select

Permanent Magnets and Electromagnets are similar in which TWO ways?

• it can be turned off and on

• they both have a north and south pole

• they are surrounded by a magnetic field

Multiple Choice

Electromagnets are useful in industry such as a junk yard because they

• have strong north and south poles

• are easy to lift

• can be turned off and on

Multiple Select

What THREE ways are electromagnets different from permanent magnets?

• they can be turned off and on

• they can increase in strength by increasing the current in the wire

• they are smaller in size

• they can change which is the north and south pole

Exploring Electric Motors

Discover the power and potential of electric motors in various applications. Learn about their efficiency, environmental benefits, and how they are revolutionizing industries.

Electric Motors:

• Definition: Devices that convert electrical energy into mechanical energy.
• Working Principle: Use electromagnetism to generate a force that causes rotation.
• Types: AC and DC motors.
• Applications: Cars, appliances, robotics, aerospace, etc.
• Advantages: Efficiency, reliability, cost-effectiveness.

Multiple Choice

What are devices that convert electrical energy into mechanical energy?

• Generators

• Transformers

• Electric Motors

• Batteries

Electric Motors

Trivia: Electric motors are devices that convert electrical energy into mechanical energy. They are widely used in various applications, including electric vehicles, industrial machinery, and household appliances. Unlike generators, which convert mechanical energy into electrical energy, electric motors work in the opposite direction. They rely on the interaction between magnetic fields and electric currents to produce rotational motion. Electric motors have revolutionized transportation and automation, making them essential in our modern world.

Electric Motors:

• Electric motors convert electrical energy into mechanical energy using loops of wire in a magnetic field.
• DC motors use direct current to produce a magnetic field, while AC motors use alternating current.
• DC motors are simpler and more efficient at producing high torque at low speeds, while AC motors can operate at higher speeds and require less maintenance.
• Electric motors are used in various applications, including household appliances, industrial machinery, and transportation.

Multiple Choice

What type of current do DC motors use to produce a magnetic field?

• Direct current

• Alternating current

• Static current

• Variable current

DC Motors

Trivia: DC motors use direct current to produce a magnetic field. Unlike AC motors, which use alternating current, DC motors provide a steady flow of electricity. This allows for precise control and efficient operation. Fun fact: The first practical DC motor was invented by Thomas Davenport in 1834.

Electric Motors:

An electric motor is an electromechanical device that converts electrical energy into mechanical energy. It consists of a rotor, stator, commutator, and field winding. When electric current flows through the field winding, it creates a magnetic field which interacts with the rotor to create torque and rotation. The commutator then reverses the polarity of the current to keep the motor rotating in one direction. AC motors are powered by alternating current and tend to be more efficient, while DC motors are powered by direct current and are simpler to control.

Multiple Choice

What is the main function of a commutator in an electric motor?

• To create a magnetic field

• To reverse the polarity of the current

• To convert electrical energy into mechanical energy

• To control the speed of the motor

Electric Motor:

Trivia: The main function of a commutator in an electric motor is to convert electrical energy into mechanical energy. It does this by reversing the polarity of the current, allowing the motor to continuously rotate in the same direction. Without a commutator, the motor would not be able to generate mechanical motion.

Exploring Electric Motors

Learn about the power and applications of electric motors. Discover how they work, their advantages, and their impact on various industries. Explore the future of electric motors and their potential for sustainable energy solutions. Get inspired to innovate and contribute to the advancement of electric motor technology.

Multiple Choice

What is the main focus of the passage 'Exploring the Power of Electric Motors'?

• Advantages and applications of electric motors

• History of electric motors

• Impact of electric motors on the environment

• Future potential of electric motors

Electric Motors: A Historical Journey

• 1834: Thomas Davenport builds the first practical electric motor.
• 1888: Nikola Tesla invents the AC induction motor.
• 20th century: Electric motors revolutionize industries like transportation and manufacturing.
• Today: Electric motors power everything from cars to household appliances.

Multiple Choice

What type of energy comes OUT of a generator?

• Electrical

• Potential

• Mechanical

• Thermal

Multiple Choice

What energy do you put IN to a generator?

• Thermal

• Mechanical

• Electrical

• Potential

Multiple Choice

Generators are devices that convert _____ energy into _____ energy.

• mechanical; electrical

• potential; kinetic

• chemical; mechanical

• electrical; mechanical

Multiple Choice

In an electric motor, the energy transformation begins as ---

• electrical and becomes chemical

• mechanical becomes electrical

• electrical and becomes mechanical

• mechanical and becomes chemical