MS-PS2-5: Magnetic and Electric Fields

MS-PS2-5
Magnetic and Electric Fields

Middle School

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Learning Objectives

• Show that magnetic and electric fields apply forces to objects without touching them.

• Explain the attraction and repulsion rules for magnetic poles and electric charges.

• Investigate fields by changing variables like distance, orientation, or strength.

• Differentiate between permanent magnets, electromagnets, and nonmagnetic materials.

Key Vocabulary

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Force at a Distance

A force that acts on an object without any direct physical contact between the two objects.

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Magnetic Field

An area of magnetic force that exists around a magnet, exerting force on other magnetic materials.

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Electric Field

An area of electric force surrounding a charged particle, which exerts a force on other charges.

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Magnetic Pole

The north or south ends of a magnet where the magnetic force is at its strongest.

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Electric Charge

A fundamental property of matter that can be either positive or negative, creating electric fields.

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Attraction

The force that pulls opposite magnetic poles or opposite electric charges toward each other.

Key Vocabulary

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Repulsion

Repulsion is the force that pushes like magnetic poles or similar electric charges away from each other.

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Permanent Magnet

A permanent magnet is a magnet that retains its magnetic properties over a very long time.

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Electromagnetism

Electromagnetism is the creation of a magnetic field that is produced by an electric current.

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Induced Magnetism

Induced magnetism is the temporary magnetism created in an object when it is close to a magnet.

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What Are Fields and Forces at a Distance?

• A field is an invisible area of force that extends through space.

• Forces like gravity and magnetism use fields to act from a distance.

• This allows objects to push or pull on each other without touching.

• A magnet moving a compass needle is evidence that a field exists.

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Multiple Choice

What is a field, in the context of forces?

• An invisible area of force that extends through space

• A force that can only be created by direct contact

• The physical connection between two touching objects

• A visible beam of energy like light or sound

Multiple Choice

What is the primary function of a force field?

• They allow objects to push or pull on each other without touching.

• They make forces like gravity and magnetism visible.

• They prevent objects from being able to move.

• They can only exist in a vacuum, not in air.

Multiple Choice

When a magnet moves a nearby compass needle without physical contact, what conclusion does this evidence support?

• An invisible field is exerting a force on the compass needle.

• The magnet must be hotter than the compass needle.

• The air between the two objects is carrying the force.

• The compass needle and the magnet are made of the same material.

Magnetic Fields

• A magnetic field is an invisible force field extending from a magnet's poles.

• The force is always strongest at the north and south poles.

• Like poles repel each other, while opposite poles attract each other.

Multiple Choice

What is a magnetic field?

• An invisible force field extending from a magnet's poles.

• A visible light that surrounds a magnet.

• The electrical charge stored inside a magnet.

• A type of gravity that only affects metal.

Multiple Choice

What happens when the south pole of one magnet is brought close to the south pole of another magnet?

• The two poles will attract each other.

• The two poles will repel each other.

• The magnetic field will disappear.

• One of the poles will reverse its polarity.

Multiple Choice

Which of the following would create the strongest force of attraction between two magnets?

• Place the north pole of one magnet close to the south pole of the other.

• Place the north poles of both magnets close together.

• Place the sides of the magnets next to each other.

• Place the south poles of both magnets close together.

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What Are Electric Fields?

• An electric field is a region of force around an electric charge.

• Objects can possess either a positive (+) or a negative (-) charge.

• Just like magnets, opposite charges, such as positive and negative, attract.

• In contrast, charges that are the same will repel each other.

Multiple Choice

What is an electric field?

• An area of force surrounding an electric charge

• A field that only affects magnetic objects

• The flow of electrons through a wire

• Energy that comes from the sun

Multiple Choice

What happens when an object with a positive charge is placed near an object with a negative charge?

• They will attract each other.

• They will repel each other.

• They will have no effect on each other.

• They will both lose their charge.

Multiple Choice

If a positively charged tape is brought near a second tape and they repel each other, what can you conclude about the second tape?

• The second object must have a positive charge.

• The second object must have a negative charge.

• The second object must have no charge.

• The second object must be a magnet.

Investigating Fields

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Distance

• ​The force of a field weakens as distance from the source increases.

• ​​A test object far from a magnet will experience a weaker pull.

• ​This shows a cause-and-effect link between distance and the field’s strength.

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Strength

• ​The strength of a source object affects the force of its field.

• ​​A stronger magnet creates a more powerful magnetic field, exerting greater force.

• ​A larger electric charge produces a much stronger electric field around it.

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Orientation

• ​The orientation of objects in a field can change the force’s direction.

• ​​For example, opposite poles of two different magnets will attract each other.

• ​Flipping one magnet around may cause the magnets to push each other away.

Multiple Choice

What is the relationship between the distance from a source and the strength of its field?

• The field's force increases as distance increases.

• The field's force weakens as distance increases.

• Distance from a source has no effect on its field's force.

• The field's force is only affected by the source's orientation.

Multiple Choice

How does the strength of a source, such as a magnet or electric charge, affect its field?

• A stronger source creates a weaker field.

• A stronger source produces a more powerful field.

• The source's strength only changes the field's direction.

• The source's strength has no impact on its field.

Multiple Choice

If two magnets are attracting each other, what action described would cause them to push each other away?

• Moving the magnets farther apart.

• Using stronger magnets.

• Flipping the orientation of one magnet.

• Placing the magnets in a warmer room.

Magnetic and Nonmagnetic Materials

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Permanent Magnets

• ​Its internal magnetic particles are always aligned in a fixed direction.

• ​​This alignment creates a magnetic field that is always present.

• ​They attract magnetic objects without needing any external influence.

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Temporary Magnets

• ​These are materials like iron that are not always magnetic.

• ​​Their magnetic particles align when a permanent magnet is brought near.

• ​This process of inducing magnetism creates a temporary magnetic field.

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Nonmagnetic Materials

• ​Materials like plastic have no magnetic properties at the particle level.

• ​​Their internal particles do not align to form a magnetic field.

• ​They are not affected by the presence of any magnetic fields.

Multiple Choice

What is the fundamental difference between a permanent magnet and a temporary magnet?

• A permanent magnet's particles are always aligned, while a temporary magnet's are not.

• A permanent magnet is made of plastic, while a temporary magnet is made of iron.

• A permanent magnet requires an external influence, while a temporary magnet does not.

• A permanent magnet has no magnetic field, while a temporary magnet does.

Multiple Choice

How does a material like iron become a temporary magnet?

• Its internal particles are always aligned in a fixed direction.

• Its internal particles align in the presence of a nearby permanent magnet.

• It is made from a material that has no magnetic properties at the particle level.

• It creates a magnetic field without any external influence.

Multiple Choice

A permanent magnet attracts an iron nail but does not attract a plastic block. Which statement provides the best explanation for this observation?

• The nail's particles align to form a temporary magnetic field, while the plastic's particles do not.

• The nail is a permanent magnet, while the plastic is a temporary magnet.

• The permanent magnet is only strong enough to attract metal objects like the nail.

• The nail has a magnetic field that is always present, while the plastic does not.

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The Principle of Electromagnetism

• An electric current in a wire produces a surrounding magnetic field.

• This principle, called electromagnetism, links electricity and magnetism.

• The strength of the magnetic field can be increased by coiling the wire.

• More loops in the coil create a stronger, more concentrated magnetic field.

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Multiple Choice

What is the principle of electromagnetism?

• An electric current flowing through a wire creates a magnetic field.

• A magnetic field can only be created by a permanent magnet.

• Electricity and magnetism are two completely unrelated forces.

• Coiling a wire reduces the flow of electric current.

Multiple Choice

What is the effect of coiling a wire that is carrying an electric current?

• It makes the magnetic field stronger and more concentrated.

• It cancels out the magnetic field completely.

• It reverses the direction of the magnetic field.

• It has no effect on the magnetic field's strength.

Multiple Choice

If you compare two electromagnets, one with a coil of 50 loops and another with 100 loops, which one will be stronger and why?

• The electromagnet with 100 loops, because more loops create a stronger magnetic field.

• The electromagnet with 50 loops, because fewer loops make the field more concentrated.

• Both electromagnets would be equally strong.

• Neither would be strong, as coils weaken the magnetic field.

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Common Misconceptions

Misconception	Correction
A force requires two objects to be touching.	Forces can be exerted at a distance through electric and magnetic fields.
All metals are attracted to magnets.	Only magnetic materials like iron are strongly attracted to magnets.
Cutting a magnet in half separates its north and south poles.	Each half becomes a smaller magnet with its own north and south poles.

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Summary

• Electric and magnetic fields are invisible forces that allow objects to interact without touching.

• The rule for both is that like poles or charges repel and opposites attract.

• We can find evidence for fields by observing their effects on test objects.

• Permanent magnets have aligned particles; electric currents in coils create electromagnets.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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