Topic 2.2-Electromagnetic Force-TN Standard: 8.PS2-2-Master

8.2.2-Electromagnetic Force

By Jessica Freeman

Topic 1 – Electricity and Magnetism: The Connection

Objective: Students will describe how electricity and magnetism are related

Engage:

Show a current-carrying wire deflecting a compass needle.

Electricity and Magnetism

​Electrons & Protons

• For your information...

• Electrons have a negative charge.

• Protons have a positive charge.​

Electric Charges

• ​ With an electric charge, it causes electrons and protons to exert forces on one another.

• ​ Particles with like charges repel one another.

• Particles with unlike charges attract each other.

• Sometimes electrons are temporarily pulled away from atoms, creating stationary areas of positive and negative charges.

• This is called static electricity

96

Magnetic Fields

Return to Table
of Contents

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

related

current -> magnetic field

current flow

the magnetic field interacts with it.

Multiple Choice

What are the invisible lines called around this model?

• Electric Field Lines

• Magnetic Field Lines

• Lettuce Seeds

Multiple Choice

As the magnets get farther apart, the strength of the fields get.....

• Weaker

• Stronger

• Stay the same

Multiple Choice

Magnetism and Electricity are both __________ forces

• Contact

• Noncontact

Multiple Choice

Magnetism and Electricity both have a __________ or region around an object where the force is applied

• Track

• Field

Multiple Choice

In both Magnetism and Electricity, Opposite charges or poles

• Attract

• Repel

Multiple Choice

In both Magnetism and Electricity, Alike charges or poles

• Attract

• Repel

Multiple Choice

Where is the force of a magnet the strongest?

• At the poles

• In the middle

• Far away from the magnet

Multiple Choice

Magnetism and Electricity both have a type of stored energy called ______ energy

• Potential

• Kinetic

Topic 2 – Solenoids

Objective: Students will describe properties of solenoids.

Engage:

Show a coil of wire with current producing a magnet-like field.

A single wire produces a weak, circular magnetic field, while a coiled wire creates a much stronger, more uniform magnetic field, similar to a bar magnet, because the fields from each loop add together.

You can visualize this with iron filings, which align along the field lines, showing concentric circles around a single wire but parallel lines inside a coil.
A compass also reveals the difference: a single wire deflects it weakly, while a coil causes a larger deflection and creates distinct north and south poles, demonstrating a stronger magnetic field. 

​Single wire vs. Coiled Wire

​Add to your notes

​coil of wire carrying a current

bar magnet

uniform

strong

Multiple Choice

The relationship between electricity and magnetism is called _____________.

• Electricity

• Law of Conservation of Energy

• Electromagnetism

• Magnetism

Multiple Choice

A _______________ is a coil that carries an electric current. 

• Solenoid

• Simple Electric Motor

• Electromagnet

• Generator

Multiple Choice

What can be done to increase the number of magnetic objects that an electromagnet picks up?

• Make the wire longer

• Remove the nail from the center of the wire

• Increase the number of coils in the solenoid

• Spread the coils out across the nail

Enlarge the Core

• You can also make an electromagnet stronger by making the iron core bigger.

• A larger diameter of the core means that there is more metal which will further magnify the strength of the magnetic field.

Multiple Choice

Which of these is not a way to increase the magnetism of an electromagnet

• Increase the length of the wire.

• Increase the thickness of the wire.

• Decrease the distance to the power source.

• Increase the distance to the power source.

Multiple Choice

Which of these is not an example of an electromagnet.

• Refrigerator Magnet

• Speakers

• Computer Hard Drive

• Generators

Multiple Select

(Choose all that apply) Which of these would decrease the power of an electromagnet?

• Decrease the distance to the power source.

• Decrease the thickness of the wire.

• Decrease the amount of current running through the wire.

• Decrease the length of the wire.

Multiple Choice

(True of False) An electromagnet is still a magnet when there is not current running through it.

• True

• False

Multiple Choice

How can you increase the magnetic field strength in an electromagnet?

• Increase the number of coils.

• increase the voltage

• increase the current by reducing the resistance of the coil

• all of the above

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

A solenoid concentrates magnetic field inside the coil → acts like a bar magnet

​A solenoid creates a concentrated, uniform magnetic field inside the coil because the magnetic fields from each individual loop of wire add up.

This combined field is similar to that of a bar magnet, with the field lines emerging from one end (the North pole) and entering the other (the South pole).

The strength of the field can be increased by adding an iron core to the solenoid. 

• Add to your notes:
  Draw solenoid with N/S poles.

Multiple Choice

A coil of wire that has a soft iron core and that acts as a magnet when an electric current is in the coils is called a/an:_____________

• temporary magnet

• electromagnet

• permanent magnet

• ferromagnet

Multiple Choice

Increasing the electric current in the wires on an electromagnet is one way to _______________.

• Strengthen a solenoid's magnetic field

• make a solenoid become an electromagnet

• make an electromagnet become a weak solenoid

• weaken a solenoids's magnetic field

Multiple Choice

Increasing the number of loops per meter in the coils of a solenoid is one way to __________.

• increase the wire's electric current

• strengthen the solenoids magnetic field

• weaken the solenoids magnetic field

• decrease the wire's electric current

Multiple Choice

Which of the following are types of magnets?

• electromagnets

• bar magnets

• horseshoe magnets

• all are types of magnets

Multiple Choice

The device represented in this diagram is called a ________.

• solenoid

• generator

• motor

• electromagnet

Multiple Choice

Increasing the electric current in the wires on an electromagnet is one way to _______________.

• Strengthen a solenoid's magnetic field

• make a solenoid become an electromagnet

• make an electromagnet become a weak solenoid

• weaken a solenoids's magnetic field

Multiple Choice

Increasing the number of loops per meter in the coils of a solenoid is one way to __________.

• increase the wire's electric current

• strengthen the solenoids magnetic field

• weaken the solenoids magnetic field

• decrease the wire's electric current

Multiple Choice

The device represented in this diagram is called a ________.

• solenoid

• generator

• motor

• electromagnet

Multiple Choice

The north and south poles of a solenoid change with

• the type of material in the core

• the number of loops in the coil

• the tightness of loops in the coil

• the direction of the current

Multiple Choice

Both solenoids and electromagnets produce magnetic fields using

• electric current and coiled wires

• compasses and magnetic fields

• coiled wires and a ferromagnetic core

• electric current and a battery

Dropdown

One way to increase the strength of a magnetic field in an electromagnet is to increase the amount of current in the wire.​

Select answer

Dropdown

One way to decrease the strength of a magnetic field in a solenoid is to change the core. ​

Select answer

Dropdown

One way to increase the strength of a magnetic field of an electromagnet is to wind the coils more closely together. ​

Select answer

Multiple Select

You can increase the strength of an electromagnet's field by (choose all that are correct)

• decreasing the current in the solenoid

• decreasing the number of loops in the solenoid

• using a stronger ferromagnetic core

• winding the coils more loosely

• increasing the number of loops in the solenoid

Multiple Select

You can increase the strength in an electromagnet's field by (choose all that apply).

• increasing the current in the solenoid

• winding the coils more tightly

• increasing the number of loops in the solenoid

• winding the coils more loosely

• decreasing the number of loops in the solenoid

Multiple Choice

Which of the following materials is commonly used as the core of an electromagnet?

• Plastic

• Wood

• Iron

• Glass

Multiple Choice

What is the primary function of a solenoid in an electric circuit?

• To store electrical energy

• To produce a magnetic field

• To resist the flow of current

• To convert electrical energy into light

Reorder

Rearrange in order of increasing magnetic strength.

• A

• C

• B

1

2

3

• 1
• 2
• 3

Topic 3 – Electromagnets

Objective: Students will explain how variables affect electromagnet strength.

Test how increasing coils or current changes paperclip count.

​

Explore

Engage:

Use a nail, wire, and battery to pick up paperclips.

• Explain:
  Factors:
  more coils
  more current,
  iron core = stronger electromagnet.

Multiple Choice

Describe the factors that affect the strength of an electromagnet.

• Temperature of the core

• Length of the wire

• Color of the coil

• Number of turns in the coil, current flowing through the coil, material of the core, and presence of external magnetic fields

Multiple Choice

Explain the process of making an electromagnet stronger.

• Increase the number of coils, increase the current, and use a core material with high magnetic permeability.

• Decrease the current

• Use a core material with low magnetic permeability

• Decrease the number of coils

Multiple Choice

How do magnetic fields interact with each other?

• Change color

• Create electricity

• Attract or repel

• Produce sound

Multiple Choice

Why are paperclips attracted to magnets?

• They contain silver

• They contain aluminum

• They contain tin

• They contain iron

Multiple Choice

A compass needle responds to a magnetic field, because the compass needle is a

• A. generator.
• B. motor.   
• C. magnet.
• D. transformer.

Multiple Choice

In order for an electromagnet to be formed, an __________ current must pass through a coil of __________ wrapped around an ________ core.

• wire, iron, electric
• electric, wire, iron
• iron, electric, wire
• excited, hair, apple

Multiple Choice

What kind of magnet can be turned on and off?

• refridgerator magnet
• electromagnet
• magnetite
• iron

Multiple Select

What are some ways to increase the strength of an electromagnet? (click all that apply)

• More coils

• Smaller battery

• Bigger battery

• Tighter coils

Multiple Choice

What is an electromagnet?

• A magnet made by aligning magnetic domains in a material

• A temporary magnet produced by passing an electric current through a coil of wire

• A magnet that always points to the north pole

• A magnet that only attracts non-metallic objects

Multiple Choice

Explain non-contact forces.

• Forces that act at a distance without physical contact between objects, such as magnetic and electric forces.

• Forces that require physical contact between objects, such as friction and tension.

• Forces that only occur in outer space.

Multiple Choice

This is a picture of a simple electromagnet. How can the electromagnet be made stronger?

• Add more coils of wire to the nail

• Use a smaller battery

• Reverse the poles of the magnet

• Remove all the coils and the nail

Multiple Choice

What would happen if you took one end of the wire off the battery?

• The nail will be a magnet

• The nail will no longer be a magnet

• Nothing will happen

• The nail will heat up

Multiple Choice

Which electromagnet is stronger?

• A

• B

Multiple Choice

Which electromagnet is stronger?

• A

• B

Match

If I build electromagnets using nails made of different metals, then I think the copper nail will pick up the most paperclips. Match the experimental variables.

• independent variable

• dependent variable

• constant

nails of different metals

number of paperclips picked up

battery

• nails of different metals

• number of paperclips picked up

• battery

Dropdown

Wrapping the wire around the nail more times would ​

Select answer

the magnetic field. 

Topic 4 – Generators

Objective: Students will explain how generators use magnetism to produce electricity.

​wire current iron core

on off

coils

current

iron

Engage:

Hand-crank generator demo → lights bulb.

​https://youtu.be/h0iSM7uVyiQ

A moving magnet within a coil of wire creates a changing magnetic field, which pushes the electrons within the wire, inducing an electric current in the coil.
The faster the magnet moves, the more rapidly the magnetic field changes, resulting in a stronger induced electric current because the electrons are forced to move at a greater rate.

This phenomenon is known as electromagnetic induction and is described by Faraday's Law of Induction, which states that a changing magnetic field produces an electric current. 

​

Multiple Choice

Would increasing the number of batteries in a circuit that is connected to a small electric motor affect the speed of the motor, if all other variables are kept constant?

• No, because it is the magnetic force, not the electric force, that controls the motor speed.

• Yes, the motor would run faster because the increased electrical force increases the magnetic force in the motor.

• No, the speed of a motor is controlled only by the number of wire coils in the motor.

• Yes, the motor would run faster because increased current causes the motor to become warmer.

Multiple Choice

A battery converts what type of energy to another?

• sound to kinetic
• light to heat
• mechanical to electrical
• chemical to electrical

Generators

a machine that gas to create electrical energy to power objects

especially important during severe weather conditions.

​

Generator

Match

Let's check our past vocabulary we will be discussing today.

• kinetic energy

• mechanical energy

• solenoid

• heat

energy of motion

energy that moves an object

a coil of wire that acts as a magnet

transfer of thermal energy

• energy of motion

• energy that moves an object

• a coil of wire that acts as a magnet

• transfer of thermal energy

a device that produces electricity by converting mechanical energy into electricity

​

​Generator

Law of Conservation of Energy says energy cannot be created or destroyed, only change or convert to a different form of energy.

​Remember....

All generators have:
1- turbine
2- solenoids
3- conductive wire

​

​Structures of a Generator

1- Solenoid - magnetic solenoids generator electrical energy as turbine spins past them
2- Turbine - a structure that turns in a circle with magnets attached
3- Conductive Wires that carry the electrical energy to where it is used.

Parts to a generator

Match

Match the part to its function.

• turbine

• solenoid

• conductive wire

provides kinetic energy input

generates electrical energy

transmits electrical energy

• provides kinetic energy input

• generates electrical energy

• transmits electrical energy

​Wind moves the blades and creates mechanical energy which then turns it into electrical energy.

​​Wind turbines

They are important during severe weather.

​​Gasoline Powered Generator

​Water turns the turbine and creates electrical energy.

​​Water Powered Generator

​Nuclear fission creates heat which in turn makes steam that turns the turbine to create electricity.

Nuclear Generator

​Types of Generators

Multiple Choice

What role do magnets play in generators?

• magnets provide kinetic energy input for generator

• magnets produce electric current when spin near solenoid

• magnets allow the electrical energy to flow to the load

• magnets connect the fuel source to the turbine

Multiple Choice

Generators convert one type of energy into another. What type of energy is present in the generator's turbines?

• potential energy

• mechanical kinetic energy

• electrical energy

• chemical energy

​ mechanical electrical

magnet

stronger

​​Add to notes

• The bar magnet has a north (N) and south (S) pole.

• The arrow shows that the magnet is being pushed through the coil of wire.

• As the magnet moves, the magnetic field lines cut across the wire loops.

• This changing magnetic field induces an electric current (I) in the coil.

• The induced current flows through the wire and can be detected with a meter, bulb, or symbol (I in the diagram).

👉 Key takeaway: A moving magnet through a coil generates electricity. This is the basis of generators and how mechanical energy is converted into electrical energy.

​Add to notes

Multiple Choice

A student wants to use the diagram below to explain what happens when the light bulb turns on. How could she best explain what is happening?

• Light energy is transformed to electric energy.

• Electric energy is transformed to light energy.

• Electric energy is transformed to motion energy.

• Motion energy is transformed to electric energy.

Multiple Choice

Which of the following energy transformations occur when a lamp is plugged into the outlet and the bulb is inserted into the lamp?

• thermal - electrical - light

• electrical - light - thermal

• light - thermal - electrical

• electrical - thermal - light

Electrical Energy

Electricity is important because we can use it to make so many things work (electrical energy). For example, a bulb converts electrical energy into light energy and a speaker converts it into sound energy.

Multiple Choice

10. A lamp begins with electrical energy when plugged in and turns into _________ energy when the light comes on.

• Mechanical (PE + KE)

• Kinetic

• Radiant (Light)

• Sound

Multiple Choice

Which one of these images represent sound energy?

Multiple Choice

The turkey is being cooked in the oven by _____ Energy.

• Thermal

• Solar

• Electrical

• None

Multiple Choice

What form of energy is this?

• Electrical

• Mechanical

• Chemical

• Thermal

Multiple Choice

Which is an example of electrical energy?

You also learned the "Law of Conservation of Energy"

​

***Energy cannot be destroyed, but it can be transformed.***

Energy changing from one form to another...

is sometimes called energy conversion or energy transformation.

​

>>> Any form of energy can change into any other form of energy.

​