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8th Grade

Types of Interactions

2015-10-27

www.njctl.org

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Table of Contents

· Electromagnetic Interactions

· Magnetic Fields

· Transfer of Forces

· Interactions between Electric Charges

Click on the topic to go to that section

· Electric Fields

· Electric Forces

· Magnetism

Slide 4 / 134

The Transfer of Forces

Return to Tableof Contents

Slide 5 / 134

Let's review Newton's Laws of Motion.

With a partner, describe Newton's Three Laws of Motion.

Record your answers on the next slide.

Forces in the Universe

Slide 6 / 134

Review: Newton's Laws

First Law:

Second Law:

Third Law:

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Work in your group to brainstorm some ways that forces can be applied to an object.

Write them down on your notes and be prepared to share your groups ideas.

What are some ways we can apply a force to an object?

QUESTION

?

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Some forces can be transferred by actually touching an object.

Other forces are able to work without touching an object, even through empty space!

Forces Acting on Objects

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Let's Classify the Forces into 2 CategoriesForces that act by Direct

Contact(by touching)

Forces that Act without Direct Contact(without touching)

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The forces that act over a distance are going to be exerted over what we call a "field". These forces are called field forces.

Definition of field (from Physics):A region of space characterized by a physical property, such as gravitational or electromagnetic force or fluid pressure, having a determinable value at every point in the region.

Forces Acting Over a Distance

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1 Which of the following is NOT an example of a force being exerted through a field?

A Gravity pulling on a falling apple

B A man pushing a car

C A magnet attracting a steel ball

D An electrically charged balloon pushing on another balloon from across the room

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1 Which of the following is NOT an example of a force being exerted through a field?

A Gravity pulling on a falling apple

B A man pushing a car

C A magnet attracting a steel ball

D An electrically charged balloon pushing on another balloon from across the room[This object is a pull

tab]

Ans

wer

B

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2 A balanced force acting on an object will cause it to accelerate (change velocity).

True

False


2 A balanced force acting on an object will cause it to accelerate (change velocity).

True

False

[This object is a pull tab]

Ans

wer

False

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Force Acting Through Fields

Is the red ball affected by Earth? What force is at work in this diagram?

Here's one example of a force acting through a field over a distance without touching .

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Newton's Universal Law of Gravitation

A teacher can even exert a force of gravitation on their students!

Click here to see a video on the Law of Gravitation

Any two objects with mass will exert a force of attraction to each other even over vast distances. This force acts on

both objects, pulling them towards each other.

Slide 15 / 134

3 What factors affect the force of gravity between two objects? (Choose all that apply.)

A mass of the objects

B weight of the objects

C distance between the objects

D force of the objects


3 What factors affect the force of gravity between two objects? (Choose all that apply.)

A mass of the objects

B weight of the objects

C distance between the objects

D force of the objects


Ans

wer

A &C

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4 What happens to the force of gravity between two objects as they move apart?

A Increases due to distance

B Decreases due to distance

C Nothing because the masses dont change

D impossible to tell without knowing what the objects are


4 What happens to the force of gravity between two objects as they move apart?

A Increases due to distance

B Decreases due to distance

C Nothing because the masses dont change

D impossible to tell without knowing what the objects are


Ans

wer

B

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5 When talking about the gravity between you and Earth, Earth has a larger force acting on it than you do.

True

False


5 When talking about the gravity between you and Earth, Earth has a larger force acting on it than you do.

True

False


Ans

wer

False

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Mathematical Relationships in Physics

Before we discuss the law of gravitation in great detail, it is important to understand basic mathematical relationships used in science. We can

"read" equations to determine how the variables in the equations affect each other.

Mathematical relationships tend to be classified into two main categories.

Directly Proportional&

Inversely Proportional

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Directly ProportionalWhat is meant by the term "directly proportional"?

Example:

A child is paid $1.00 per paper delivered on his/her newspaper route. If they deliver more papers, they earn more money.

This works in reverse as well, if the child's bicycle chain breaks and they deliver less papers, then he/she makes less money.

In an equation, as one amount increases, another

amount increases at the same rate.

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Inversely Proportional

In an equation, as one amount increases, another amount decreases at the

same rate.

Example:

As the paperboy increases his/her speed of delivery, the time it takes to complete his/her route decreases!

And as the paperboy decreases his/her speed of delivery, the time it takes to complete his/her route increases!

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6 A person increases their distance away from a light bulb, the observed brightness decreases. What is the mathematical relationship observed during this event?

A Inversely Proportional

B Directly Proportional


6 A person increases their distance away from a light bulb, the observed brightness decreases. What is the mathematical relationship observed during this event?




Ans

wer

A

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7 A college student increases her time studying. Her test grades also increase. What is the relationship between time studying and earned grades?




7 A college student increases her time studying. Her test grades also increase. What is the relationship between time studying and earned grades?




Ans

wer

B

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8 As the voltage in a circuit is increased, the amount of electrical current is also increased. What is the mathematical relationship observed during this event?



(Answer) / 134

8 As the voltage in a circuit is increased, the amount of electrical current is also increased. What is the mathematical relationship observed during this event?




Ans

wer

B

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9 As the resistance in a circuit is increased, the amount of electrical current is decreased. What is the mathematical relationship observed during this event?




9 As the resistance in a circuit is increased, the amount of electrical current is decreased. What is the mathematical relationship observed during this event?




Ans

wer

A

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10 We know that the force of gravity between two objects increases as the masses get larger. This relationship is ___________ proportional.

A directly

B inversely


10 We know that the force of gravity between two objects increases as the masses get larger. This relationship is ___________ proportional.

A directly

B inversely


Ans

wer

A

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Compare the force of gravity acting on you (your weight) on Earth compared to the moon:

Which is larger? WHY?

Comparing Forces of Gravity

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A B C

What happens to the force of gravity on an object as we move farther away from a massive object like Earth?

With your group, compare the force of gravity (weight of boy) at points A, B, & C and be ready to share.

Comparing Forces of Gravity

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The force of gravity exerted by an object decreases as it moves away from an object like Earth.

As the boy moves away from Earth, his weight will decrease.

Distance and Forces of Gravity

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11 As the same boy from the last slide moves farther from Earth, will his mass change?

Yes

No


11 As the same boy from the last slide moves farther from Earth, will his mass change?

Yes

No


Ans

wer

No

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Why can't we feel the forces of Gravitation acting between two people?

Small Masses = Small Force of Gravitation

Even though there is always a gravitational force acting between masses, it is only noticeable when the objects' masses are

relatively large.

If we were to compare our mass to that of a planet, a person's mass is so small that the gravitational force they produce is

almost unmeasurable.

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12 The force of gravity _________ as the object's mass increases.

A Increases

B Remains Constant

C Decreases

(Answer) / 134

12 The force of gravity _________ as the object's mass increases.

A Increases

B Remains Constant

C Decreases


Ans

wer

A

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13 The force of gravity _________ as the distance between two objects increases.

A Increases

B Remains Constant

C Decreases


13 The force of gravity _________ as the distance between two objects increases.

A Increases

B Remains Constant

C Decreases


Ans

wer

C

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The force of gravity does not decrease at a constant rate as an object moves away from a planet.

The Force of Gravity actually decreases exponentially as distance increases!


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If we graph the force of gravity (Newtons) vs. distance of separation (m) of an object as it moves away from a planet, this is what we get:


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The decrease in the force of gravity does not decrease at a constant rate. If it did the graph would look like this:

Note: This graph is not the real pattern we observe in nature.


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14 Force is ___________ proportional to distance.

A Directly

B Indirectly


14 Force is ___________ proportional to distance.

A Directly

B Indirectly


Ans

wer

B

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The true pattern observed by scientists showed that the force of gravity is inversely proportional to distance of separation squared!


F = 1 d2

NOTE: This is almost the same as regular inversely proportional,

but the force decreases much more as distance increases

because it is squared.

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Putting it all together

Putting all these ideas together, fill in the blanks below with the correct mathematical relationships.

d

The Gravitational Force between 2 masses is

__________________ to the product of the masses and

________________ to the distance of the separation squared

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We can represent the gravitational field around a mass with lines of force.

The lines point inward and then spread apart as we move away from Earth.

Why? Come up with an idea with your table.

Gravitational Field Lines

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15 The force of gravity decreases at a constant rate as we move away from a planet like Jupiter.

True

False

(Answer) / 134

15 The force of gravity decreases at a constant rate as we move away from a planet like Jupiter.

True

False


Ans

wer

False

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16 As we move away from the Sun, the force of gravity gets weaker by an inverse of the:

A distance cubed

B distance

C distance squared


16 As we move away from the Sun, the force of gravity gets weaker by an inverse of the:

A distance cubed

B distance

C distance squared


Ans

wer

C

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Interactions Between Electric Charges


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There are two types of electric charges:

positive and negative

What is Electric Charge?

Electric charge is the physical property of matter that causes it to experience a force when close to other electrically charged

matter.

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Positive or Negative?

Do you know who coined the terms positive and negative charge?

Remember all atoms are composed of 3 basic subatomic particles.

What were those particles?

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Objects that are positively charged are out of balance, meaning they have more protons than electrons.

+ - ++ + -+ + +

Since the box has more protons (+) than electrons(-), it is POSITIVELY CHARGED.

Positive Charge

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Objects that are negatively charged are out of balance, meaning they have more electrons than protons.

Since the box has more electrons(-) than protons (+), it is NEGATIVELY CHARGED.

Negative Charge

+ - ++ - -- - -

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Chemistry Connection

Click on the simulation image to the left.

Hit the green plus sign on NET CHARGE to show the overall charge on the atom.

What gives an atom a net:

a) positive charge?b) negative charge?c) neutral charge?

Note the effect on net charge when you:

Add protons Add electrons Add neutrons


Chemistry Connection

Click on the simulation image to the left.

Hit the green plus sign on NET CHARGE to show the overall charge on the atom.

What gives an atom a net:

a) positive charge?b) negative charge?c) neutral charge?

Note the effect on net charge when you:

Add protons Add electrons Add neutrons

Teac

her N

otes

[This object is a teacher notes pull tab]

Choose the "run in HTML 5" option.

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17 What makes an object exhibit an overall positive charge?

A more protons in the object

B more electrons than protons in the object

C more protons than electrons in the object

D less electrons in the object


17 What makes an object exhibit an overall positive charge?

A more protons in the object



D less electrons in the object[This object is a pull tab]

Ans

wer

C

http://phet.colorado.edu/en/simulation/build-an-atom

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18 What makes an object exhibit an overall negative charge?

A equal protons and electrons in the object





18 What makes an object exhibit an overall negative charge?





Ans

wer

B

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19 What makes an object exhibit an overall neutral charge?






19 What makes an object exhibit an overall neutral charge?





Ans

wer

A

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Electric Forces


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There is one very common way we can see forces between charged objects. You can see it in the picture of the boy below. You might

also experience it when you take clothes out of a dryer.What is it?

Click here to launch a simulation to explore charging and forces between charges

Forces Between Charged Objects

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In the activity where you had a balloon and a sweater, what happened when you rubbed the balloon on the sweater and then let it go?

Just like we saw with masses, forces are exerted between charges!

This is called Coulomb's Law!

Coulomb's Law

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20 Opposite charges repel.

True

False


20 Opposite charges repel.

True

False


Ans

wer

False

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21 An electron and a proton are attracted to each other.

True

False


21 An electron and a proton are attracted to each other.

True

False


Ans

wer

True

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The interaction between charged objects is a non-contact force that acts over some distance of separation. We call this an electrostatic force.

Unlike Charges Attract!

Opposite Charges Repel

Click here to see a video on Fun with Static Electricity

Electrostatic Force

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Electrostatic Force

1) Charge of the Objects

2) Distance between the 2 objects

There are 2 main factors which play into electrostatic forces.

What other force does this remind you of?

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Forces between like charges

As the amount of charge increases, what happens to the magnitude (strength) of the force?

+1 +1

+2+1

Slide 59 / 134

+1 +1

+2+1

We observe that the force of repulsion doubles when one of the charge doubles.

Electrostatic Force

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22 Electrostatic force is __________ proportional to the amount of charge present.

A directly

B inversely


22 Electrostatic force is __________ proportional to the amount of charge present.

A directly

B inversely


Ans

wer

A

Slide 61 / 134

The Electrostatic Force direction between 2 charged objects is proportional to the product of their charges.

Charge1

Charge 2

Sign of Product Type of force felt

+ + + Repulsion

- - + Repulsion

+ - - Attraction

Electrostatic Force

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As the charges move farther apart, the force between them is decreased.

What do you think happens to the force between charges when we move them father apart?

Talk about this at your table.

+ +d

Slide for the answer!

Discussion Question

Slide 63 / 134

Force between charges reduces as the charges move

apart.

Does this graph look familiar?

Electrostatic Force

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Putting it all together

The Electric Force between 2 charges is directly proportional to

the amount of charge!

It also decreases in strength as the charges move farther apart.

Slide 65 / 134

23 As the amount of charge increases, the force between the charges __________.

A decreases

B stay the same

C increases


23 As the amount of charge increases, the force between the charges __________.

A decreases

B stay the same

C increases


Ans

wer

C

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24 As the amount of distance between charges increases, the force between the charges __________.

A decreases

B stay the same

C increases

(Answer) / 134

24 As the amount of distance between charges increases, the force between the charges __________.

A decreases

B stay the same

C increases


Ans

wer

A

Slide 67 / 134

How is Coulomb's Law (forces between charges) similar/different to Newton's Law of Gravitation (forces between masses)?

Similarities Differences

Ans

wer

Slide 68 / 134

Electric Fields


Slide 69 / 134

These forces can be visualized by drawing lines that represent the forces acting between charges.

Electric Field Diagrams

We will call these electric field diagrams.

Slide 70 / 134

1) Lines exit positive charges.2) Lines enter negative charges.3) Lines don't exist around neutral charges.4) Lines never cross!5) Lines that are close together represent stronger forces.

Five Rules for Electric Field Lines

Slide 71 / 134

Field lines between like charges

Both diagrams help us visualize repulsive forces.

Do you see how the lines look like they are pushing apart at

their closest points?

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Field Lines between unlike charges

This diagram indicates electrostatic attraction.

The field lines exit the positive charge and enter the negative

charge.

Unlike the field lines between like charges, these lines look like

they are pulling together.

Slide 73 / 134

Two Oppositely Charged Metal Plates

Look at the diagram to the right.

What can be said about the spacing and direction of the field

lines between the plates?

What does this mean?


Two Oppositely Charged Metal Plates

Look at the diagram to the right.

What can be said about the spacing and direction of the field

lines between the plates?

What does this mean?


Ans

wer

The spacing of the field lines are uniform. Therefore, the field strength is the same at all points between the charged plates.

Slide 74 / 134

25 Electric field lines exit positive charges and enter negative charges.

True

False


25 Electric field lines exit positive charges and enter negative charges.

True

False


Ans

wer

True

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26 The electric field strength between 2 parallel oppositely charged plates:

AIncreases as you move towards the postive plate

B decreases as you move toward the negative plate

C remains constant at all points between the plates.

(Answer) / 134

26 The electric field strength between 2 parallel oppositely charged plates:

AIncreases as you move towards the postive plate

B decreases as you move toward the negative plate

C remains constant at all points between the plates. [This object is a pull tab]

Ans

wer

C

Slide 76 / 134

Mass ChargeAttraction Repulsion

Newton and Coulomb ComparisonIf they are used for both laws place the term on the line.

Coulomb's LawNewton's Law

Slide 77 / 134

Magnetism


Slide 78 / 134

The Discovery of Magnetism

Legend has it that Magnes was herding his sheep in an area of Northern Greece called Magnesia, about 4,000 years ago.

The most popular legend accounting for the discovery of magnets is that of an elderly Cretan shepherd named Magnes.

What do you think was special about that rock?

Suddenly both the nails in his shoes and the metal tip of his staff, became firmly stuck to the large black rock on which he was standing.

Slide 79 / 134

To find the source of attraction he dug up the Earth to find lodestones (load = lead or attract).

Lodestones contain magnetite, a natural magnetic material Fe3O4.

This type of rock was subsequently named magnetite, after either Magnesia or Magnes himself.

Magnetic Rocks?

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What is Magnetism?Magnetism is a class of physical phenomena that includes forces exerted by magnets on other magnets.

It has its origin in electric currents.

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27 Magnetism is a _________ force.

A contact

B field

C neither


27 Magnetism is a _________ force.

A contact

B field

C neither


Ans

wer

B

Slide 82 / 134

William Gilbert

William Gilbert made 2 profound discoveries: Earth was a giant magnetand also that magnets could be produced by beating wrought iron!

A scientist named William Gilbert is given credit to understanding

magnetism.

Slide 83 / 134

Magnetic Domains

A magnetic domain is a microscopic region within a magnetic material which has uniform magnetization.

This means that the individual magnetic regions of the atoms are aligned with one another and they point in the same

direction.

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Non-Magnetized Substances

If the magnetic domains (microscopic magnetic regions) are randomized, the substance will have no overall magnetic properties.

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Magnetized Substances

If the magnetic domains (microscopic magnetic regions) are aligned, the substance will have overall magnetic properties and act as a magnet.

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Permanent Magnets

Materials that can be magnetized, which are also the ones

that are strongly attracted to a magnet, are called

ferromagnetic.

A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field.

Slide 87 / 134

Ferromagnetic Substances

These include iron, nickel, cobalt, some alloys of rare earth metals, and some naturally occurring minerals such as lodestone.

On the periodic table of Elements, these 3 elements are grouped together. Is this just a coincidence?

Slide 88 / 134

Temporary Magnets

Temporary Magnets simply act like permanent magnets when they are within a strong magnetic field.

Unlike permanent magnets however, they loose their magnetism when the field disappears. Paperclips, iron nails and other similar items are examples of temporary magnets.

Slide 89 / 134

Un-Magnetized Iron-Domains are random

Magnetized Iron-Domains are aligned

Magnetizing an Iron Nail

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Electromagnets have a soft metal core made into a magnet by the

passage of electric current through a coil surrounding it.

Unlike permanent magnets however, they lose their

magnetism when the current disappears.

Electromagnets

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28 Michael Faraday discovered Earth was a giant magnet.

True

False

(Answer) / 134

28 Michael Faraday discovered Earth was a giant magnet.

True

False


Ans

wer

False

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29 Microscopic regions inside iron are called:

A magnetic crystals

B magnetic domains

C magnetic atoms


29 Microscopic regions inside iron are called:

A magnetic crystals

B magnetic domains

C magnetic atoms


Ans

wer

B

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30 Ferromagnetics substances include: (select all that are ferromagnetic)

A iron

B aluminum

C nickel

D cobalt


30 Ferromagnetics substances include: (select all that are ferromagnetic)

A iron

B aluminum

C nickel

D cobalt


Ans

wer

A, C, D

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31 An electromagnet produces a magnetic field when current stops flowing through it.

True

False

(Answer) / 134

31 An electromagnet produces a magnetic field when current stops flowing through it.

True

False


Ans

wer

False

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32 Soft Iron is an example of________________.

A an electromagnet

B a temporary magnet

C a permanant magnet

D a superconductor


32 Soft Iron is an example of________________.

A an electromagnet

B a temporary magnet

C a permanant magnet

D a superconductor


Ans

wer

B

Slide 96 / 134

Magnetic Fields


Slide 97 / 134

Magnetic Poles

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

Slide 98 / 134

Forces between Magnetic Poles

Opposite magnetic poles attract. Like magnetic poles repel.

Click here to launch a video on magnetic levitation

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/ 134

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.

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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 PolesEarth's Geographic

South Pole is actually a Magnetic North Pole!

Slide 101 / 134

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?

Slide 102 / 134

3 Magnetic Field Line Rules

Lines exit North Poles and enter South Poles

Closer lines equal stronger force

Field lines never cross!

Slide 103 / 134

As we move away from a magnetic pole, What

happens to the strength of the magnetic field?

A BCompare the spacing of the field lines

at A vs. B

What do you notice?

Magnetic Field Drawings

Slide 104 / 134

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.

/ 134

33 This photo depicts magnets which could be aligned _______________.

A North North

B North South



A North North

B North South


Ans

wer

A

Slide 106 / 134


A North North

B North South



A North North

B North South

[This object is a pull tab]A

nsw

er

B

Slide 107 / 134

Magnetic Fields Lines

Can you visualize the photos you just saw with

these drawings?

Slide 108 / 134

Attractive force between unlike poles

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

/ 134

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

Slide 110 / 134

A

B

A compass placed into the magnetic field will act as a "test magnet" and swing to line up with the direction of the magnetic

field around a magnet

In Boxes A & B, draw a compass that shows the direction of the field around the magnet.

Test Magnet

Slide 111 / 134

35 Like magnetic poles:

A attract

B repel

C don't interact


35 Like magnetic poles:

A attract

B repel

C don't interact


nsw

er

B

Slide 112 / 134

36 This type of field drawing represents:

A attraction

B repulsion

C suspension


36 This type of field drawing represents:

A attraction

B repulsion

C suspension


Ans

wer

A

/ 134

37 A test compass at A will be oriented like:

A

B

C

D

A


37 A test compass at A will be oriented like:

A

B

C

D

A


Ans

wer

A

Slide 114 / 134

38 A test compass at B will be oriented:

A

B

C

D

B


38 A test compass at B will be oriented:

A

B

C

D

B


nsw

er

A

Slide 115 / 134

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

True

False


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

True

False


Ans

wer

False

/ 134

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

A Increase

B Decrease

C Stay the same


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

A Increase

B Decrease

C Stay the same


Ans

wer

B

Slide 117 / 134

Electromagnetic Interactions


Slide 118 / 134

Magnetism and ElectricityIn 1820, Hans Christian Oersted, a Danish Physicist,

demonstrated that magnetism was related to electricity.

By bringing a wire carrying an electric current close to a magnetic compass he noticed a deflection of the compass needle.

Slide 119 / 134

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!

Slide 120 / 134

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

The magnitude of magnetic field produced by a straight current-carrying 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

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Simulating the affect of current on the magnetic field produced around a wire

Click on the picture to the left to launch the simulation.

Click Electromagnet on the top.

Change # of loops to 1, click show field meter.

Vary the voltage to change the amount of current

What happens to the field strength as we change current?

What happens to the field strength as we move the meter away from the loops?

Slide 122 / 134

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.

Slide 123 / 134

The Right Hand Rule

I

B

Grab a wire with your right hand with your thumb pointing in the same direction as the current.

Your fingers point in the direction of the magnetic field!

Slide 124 / 134

If we look down the wire, from either end, the magnetic field will turn clockwise (CW) or counter-clockwise (CCW)

Visualizing Magnetic Fields

Slide 125 / 134

Magnetic Field Around a Coil

The magnetic field around a coil is similar to the field that we see around a bar magnet.

Slide 126 / 134

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

http://phet.colorado.edu/sims/faraday/magnets-and-electromagnets_en.jnlp

http://njc.tl/t6

/ 134

What happens when we move a bar magnet near a wire/coil?

Slide 128 / 134

Let's run a simulation to explore what happens

Click on the image to the left to launch the simulation.

Move the bar magnet through the coil. What happens in the coil?

Move the coil around the magnet. What happens in the coil?

This process of producing electricity from magnetism is called "Induction".

Slide 129 / 134

Electrical Current and Magnetic Field

How might this be put to use in our modern society?

We have seen that moving magnetism can can produce an electrical current in a wire.

Slide 130 / 134

Michael Faraday- The Father of Electromagnetism

British physicist and chemist, best known for his discoveries of electromagnetic induction and of the laws of electrolysis. His biggest

breakthrough in electricity was his invention of the electric motor.

Click here to see a video on Michael Faraday's Electromagnetism

Slide 131 / 134

41 Moving electricity causes a magnetic field to form.

True

False


41 Moving electricity causes a magnetic field to form.

True

False


Ans

wer

True

http://phet.colorado.edu/sims/faraday/faraday_en.jnlp

http://njc.tl/t7

/ 134

42 The __________ rule is the rule that relates the direction of a magnetic field surrounding a wire carrying current.

A left thumb

B right hand

C right arm

D left hand


42 The __________ rule is the rule that relates the direction of a magnetic field surrounding a wire carrying current.

A left thumb

B right hand

C right arm

D left hand[This object is a pull tab]

Ans

wer

B

Slide 133 / 134

43 The father of modern electromagnetic theory is:

A Ben Franklin

B Sir Isaac Newton

C Michael Faraday

D Richard Feinman


43 The father of modern electromagnetic theory is:

A Ben Franklin

B Sir Isaac Newton

C Michael Faraday

D Richard Feinman


Ans

wer

C

Slide 134 / 134

44 The ________ rule is used to determine the direction of the magnetic field around a current carrying coil.

A right hand

B left hand

C right thumb

D left thumb


44 The ________ rule is used to determine the direction of the magnetic field around a current carrying coil.

A right hand

B left hand

C right thumb

D left thumb [This object is a pull tab]

Ans

wer

B

8th grade - njctlcontent.njctl.org/courses/science/8th-grade-science/types-of... · slide 1 / 134...

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