Science Study Guide: Electricity and Magnetism

Describe the magnetic poles: strength, type

There are two magnetic poles on a magnet. The two magnetic poles are North and South. The North Pole and the South Pole attract each other, but they repel their similar poles.

Describe magnetic field lines: direction, where are they strongest and how can you tell, where are they weakest and how can you tell?

Magnetic field lines always go from North to South. They are the strongest at the poles because the field lines are the closest together here. They are weakest at the sides of the magnet because this is where the field lines are the most spread out.

If two objects have increased charges on them, what happens to the strength of the electrical force? What will happen to the magnitude of the force if the particles get closer together? What happens to magnetic force as magnets move apart from each other?

When two objects have increased charges, the strength of the force will increase. If the particles get closer together, the magntiude of the force on the particles will also increase. As the magnets move apart from each other, their fields seperate.

If you look at iron filings around two un-marked magnets, how could you tell if the magnet poles were north to north or north to south? What would you expect to see in each case with the iron filings? Draw a picture of each scenario.

You could tell if the poles were opposite because the iron fillings would be attracted to them, and you could tell if they were similar because the iron fillings would repel from them.

How are electric motors used in everyday life?

There are electric motors in cars. They make the windows go up and down, they make the windshield wipers move, and much more.

What is a magnetic field?

A magnetic field surrounds a magnet and attracts or repels objects without touching them.

What is a magnetic material? What is a ferromagnetic material?

A magnetic material is any material that is strongly attracted to a magnet. Ferromagnetic materials are elements, including iron, nickel, and cobalt, that have an especially strong attraction to magnets.

What is an electric field? Describe the type of force electrical fields can apply to other objects.

An electric field surrounds a charged object. They can attract and repel objects without the two objects touching.

What is an electromagnet? List 3 ways that an electromagnet is it different from a permanent magnet?

An electromagnet is made by placing a ferromagnetic material, such as iron, as a core within the wire coil. Some of the ways that it is different is that the magnetic field of the coil causes the ferromagnetic core to become a magnet. The core of the electromagnet also can increase the strength of the coil's magnetic field. This makes the electromagnet's force stronger. Andas the number of loops in the coil increases, the magnetci field of the electromagnet becomes stronger.

List the steps on how to make an electromagnet.

An electromagnet is made by placing a ferromagnetic material, such as iron, as a core within the wire coil. The magnetic field of the coil causes the ferromagnetic core to become a magnet.

What type of particles are moving in an electric current? What determines the direction of the force on the wire?

Charged particles move through a current carrying wire. The direction of the force depends on the direction of the magnetic field ad the direction of the direction of the current.

Describe Earth's magnetic field: Why does Earth have a magnetic field (what is causing it?) How does it benefit life on Earth?

Earth's magnetic field has both North and South ends. Earth has a magnetic field because it has molten iron and nickel in its outer core. It benefits life on Earth because it blocks out charged particles from the Sun that could severely damage the environment over time.

Contrast Earth's magnetic poles to Earth's geographic poles.

Earth's magnetic poles and geographic poles are not in the same spot. You cannot use a compass for Earth's geographic poles, you can only use it with the Earth's magnetic poles.

Describe how electrically charged objects interact: oppositely charged objects interact in what way? Similarly charged objects interact in what way?

Electrically charged objects will either attract or repel each other. Oppositely charged objects attract each other, while similarly charged objects repel each other.

What produces the magnetic field around a current-carrying wire? What is a current-carrying wire? What happens to the magnetic field as the electric current increases?

In a current-carrying wire, the magnetic fields of the flowing charges combine to produce a magnetic field around the wire. The magnetic field around a current-carrying wire forms closed circles. Because negatively charged electrons are moving in the wire, the magnet applies a force to the moving charges.

When does a magnetic material behave like a magnet? What has to happen to the magnetic fields of the atoms in the material for it to act as a magnet?

It behaves like a magnet when both the magnet and the magnetic material's domains align and combine. The magnetic fields have to combine and the domains has to line up.

How can a neutral atom become positively charged? How can it become negatively charged? What are charged atoms called?

It can become positively charged when it loses electrons and ends up with a larger amount of protons. It becomes negatively charged when it loses protons and ends up with more electrons. Charged atoms are called ions.

Why is a compass needle attracted to magnetic fields? Does it always point to the poles? Explain why or why not.

It is attracted to magnetic fields because they exert a force on the needle and cause it to rotate. It doesn't always point to the poles because the poles are always in different places.

Describe the interaction between charged particles: How do oppositely charged particles interact? How do like-charged particles interact? How do charged particles interact with neutral particles?

Oppositely charged particles attract each other. Like-charges particles repel each other. Charged particles do not attract or repel neutral particles.

List and describe the particles in an atom: name, location, charge

Protons are positively charged and they make up the nucleus of an atom, as well as neutrons. Neutrons are not electrically charged. Electrons are negatively charged and they move around the nucleus.

Electric motors spin. What is making it spin? Discuss the role of the electromagnet, like and unlike poles.

Recall that one useful property of electromagnets is that their magnetic poles easily can be reversed. This property of electromagnets is what makes an electric motor spin.

Describe the forces between magnetic poles: how do similar poles interact? How do opposite poles interact?

Similar poles repel each other and opposite poles attract each other.

Compare and contrast temporary and permanent magnets.

Temporary: the material is only magnetized when it is close to a magnetic filed. Once it leaves, it becomes normal again. Permanent: always magnetized, even when they are removed from a magnetic field

What is the charge on an atom? Why (discuss the proton and electron count in relation to each other).

The charge on an atom is neutral, because there are equal numbers of positive charges (protons) and negative charges (electrons).

How do magnetic fields and electric currents affect a compass needle? Why?

The compass needle is a tiny magnet and will point in the direction of the field and current because it is being attracted to it.

What happens to the magnetic domains in a nail when it comes close to a magnet?

The magnetic field begins to point in the same direction as the magnet's domains.

Describe the magnetic fields formed when opposite poles are near each other. Describe them when same poles are near each other.

The magnetic fields attract each other when opposite poles are near each other. The magnetic fields repel each other when similar poles are near each other.

What happens to the strength of the magnetic force with distance?

The magnetic force will get weaker when the distance increases.

What factors affect the magnetic strength of an electromagnet? How can the strength be increased - state two ways.

The size of the metal core and the number of could increase the strength of an electromagnet.

What two factors affect the strength of the electric force between objects? How does each factor affect the strength of the electric force? Does it increase it or decrease it?

The strength of the electric charge depends on the total amount of charge on both objects and the distance between the objects. The stronger the amount of charge, the stronger the electric force is. The electric force is weaker or decreases when the distance between the two objects increases.

Where is the strongest part of an electrical field?

The strongest part is near the charges themselves.

Why are most objects/materials non-magnetic? Talk about the magnetic field of the atoms in most objects.

They are all mostly nonmagnetic because the magnetic field of all the atoms inside the objects and materials dont point in the same direction; they point in many different and random directions

How do objects become electrically charged? What causes an object to become negatively charged? What causes an object to become positively charged?

They become electrically charged when electrons move from one object to another. An object is negatively charged when it has more electrons than protons. An object is positively charged when it has more protons than electrons.