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Science magnetism and electromagnetism flashcards

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1
Q

Where does magnetism originate?

A

In an atom. It has to do with the behavior and arrangement of the electrons.
* electrons are the key to magnetism

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2
Q

Magnets

A

Materials that attract and repel other magnets and have their domains aligned. They are made of iron, cobalt, or nickel and attract other materials made of this.

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3
Q

What is magnetism?

A

A property of matter not all things have. It is also a force; the attraction or repulsion of magnetic materials.

*Not a charge, not a type of energy

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4
Q

What are magnetic domains?

A

Groups of atoms that act in the same way and have their north/south poles arranged in the same direction.

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5
Q

What is electron spin configuration?

A

Electron spin is a property electrons have so that electrons behave as if they were spinning. Electrons that are spinning produce a magnetic field, making the electrons behave like little magnets in atoms.

all behave the same way

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6
Q

What happens when domains are randomly aligned?

A

It is not a magnet but is magnetic (like a paperclip)

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7
Q

What happens when domains are aligned?

A

The material is a magnet (magnetized)

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8
Q

If a material contains iron, cobalt, or nickel….

A

It is magnetic but not necessarily a magnet unless its domains are aligned

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9
Q

A way to think of magnetic domains is…

A

That they are little jigsaw puzzle pieces that make up magnetic materials and magnets. They have to be aligned for it to be a magnet. (aka magnetized)

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10
Q

What is a material called that can become magnetized (or is attracted to magnets)?

A

Ferromagnetic material such as iron, nickel, and cobalt (its domains are capable of being aligned)

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11
Q

What are the naturally occurring elements that are ferromagnetic materials?

A

Iron, nickel, cobalt

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12
Q

What poles attract?

A

Opposite poles attract. North pole attracts to the south pole

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13
Q

What poles repel?

A

Like poles repel. North pole and north pole repel. South pole and south pole repel.

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14
Q

How/why is Earth a magnet?

A

This is because it has an active ferromagnetic core. There is molten material that circulates in the core. The internal motion of Earth causes it to have a magnetic field. Compasses work because the Earth’s magnetic field exerts force on them.

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15
Q

What is a compass?

A

A small magnet that is free to rotate and line up with a magnetic field that is influencing it.
A device used for navigation. Compasses use a magnetized needle that spins freely and will usually point north.

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16
Q

What are the four main poles?

A

North and South magnetic poles and North and South Geographic poles

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17
Q

What poles change location?

A

Magnetic poles change location throughout the years.

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18
Q

What poles stay in the same location?

A

Geographic poles stay in the same spot.

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19
Q

The geographic poles and magnetic poles are in different locations, true or false?

A

True, they are in different locations in the northern and southern hemisphere.

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20
Q

Does a compass point you to the geographic poles?

A

No, a compass will not point you to the geographic north and south, so you have to know the angle of magnetic declination to figure out where geographic north or south is when using a compass.

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21
Q

What is magnetic declination?

A

Magnetic declination is the angle between the lines going from you to the geographic north and from you to the north which the compass needle points at.

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22
Q

Where is the magnetic field the strongest?

A

At its poles.

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23
Q

What is a magnetic field?

A

The area of magnetic force around a magnet.

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24
Q

Where are magnetic poles found on magnets?

A

The magnetic poles are found at the two ends of the magnets.

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25
How are magnetic fields represented in illustrations?
Magnetic fields are represented in illustration by using red magnetic field lines that spread from one pole, curve around the magnet, and return to the opposite pole. Arrows are also used to show the direction of the magnetic field. The arrows always leave the north pole and enter the south. When the magnetic field lines increase proximity, becoming closer together and at the poles of the magnet, they have a stronger magnetic force.
26
How can a paperclip which is magnetic, become a magnet?
You would have to rub a magnet across the paperclip in the same direction to align its domains and create a magnet.
27
What are alloys and can they be made into magnets?
Alloys are a combination of metals and yes they can become magnets.
28
What are three things that can happen to a material when talking about magnetism?
Magnets can be made (magnetizing a paperclip using another magnet) Magnets can be destroyed (drop or strike a magnet hard, extreme heat, makes domains unaligned) Magnets can be broken (break magnets into smaller pieces, each smaller piece will still have their own North and South poles)
29
What is it called when a material is a magnet for a short time?
Temporary magnet
30
What is it called when a material holds its magnetism for a long time?
Permanent magnet
31
What happens to the magnetic poles in a magnet that has been broken?
When a magnet is broken in half, then there would be two magnets with its own North and South pole. Each of the magnets, no matter how small you break them, will have its own North and South pole because of the strong magnetic force from the magnetic domains being aligned in the same direction.
32
What is the magnetosphere and what would earth be like if there was no magnetosphere?
The magnetosphere is the region of Earth's magnetic field that is shaped by the solar winds. If earth had no magnetosphere then there would be no magnetic field to protect the Earth from solar winds. This would result in great damage to our planet and our existence.
33
What are van belts?
Van Allen belts are two donut shaped regions above Earth's surface which contain electrons and protons that travel at high speeds.
34
What is solar wind?
Solar wind is a stream of electrically charged particles flowing at high speeds from the sun.
35
What are auroras evidence of?
The Northern lights (aurora borealis in the Northern Hemisphere) and the Southern lights (aurora australis in the Southern Hemisphere).
36
What are auroras?
Auroras are evidence of high speed, charged particles interacting with atoms in our atmosphere. This interaction makes the atoms give off light.
37
What did Hans Christian Oersted do that contributed greatly to our understanding of electromagnetism?
Hans Christian Oersted was a teacher at a university. He was creating an electrical current with a wire and then put a compass near it. He found that the compass needle changed direction. Hans then puts multiple compasses around the wire and the needles line up to create a circle. This discovery represented how magnetism and electricity are related. *The fact that a current-carrying wire could produce a magnetic field was discovered
38
What can an electric current do?
An electric current produces a magnetic field. The relationship between electricity and magnetism is called electromagnetism.
39
If a electric current flows through a circuit with a straight wire it will....
Generate a weak magnetic field to the sides of the wire.
40
What does current direction determine?
Where the manetic poles are.
41
If you reverse the direction of the current you....
Reverse the magnetic poles.
42
How would you make the solenoids magnetic field stronger.
Coiling up the solenoid closer together and/or adding more coils.
43
What is a solenoid?
A solenoid is a coiled wire with a current running through it. Solenoids have two ends that are like north and south poles which change with the direction of the current.
44
What is a electromagnet?
A solenoid with a ferromagnetic core.
45
What can electromagnets do that are handy in real life?
An electromagnet can be turned on and off with a switch. This makes it handy to have a magnet that can be used to move things only when needed. Very powerful electromagnets are used in industry to move very heavy things.
46
How can you make the magnetic field of an electromagnet stronger?
Increase the voltage of the current.
47
What is electromagnetic induction?
Magnetic fields can move electrons in a wire (pole of magnet moves electrons in a line in one direction) *movement of electrons is electricity This is when you generate an electric current from the motion of a conductor through a magnetic field. Take magnet and a solenoid to make electricity
48
What is a generator/ what does it do?
A generator is a device that transforms mechanical energy into electrical energy. Generators take motion in a magnetic field and create an electrical current. changing distance between solenoid and magnet (motion) will create electricity (movement of electrons)
49
How do power plants use electromagnetic induction?
Power plants make electricity flow using electromagnetic induction.
50
What is motor/ what does it do?
An electric motor is a device that uses electric current to turn an axle. A motor works by reversing the current every half turn so that the wire can have a continuous spin in the same direction. For example if the loop was moving up on the left, the current would be reversed and then it would start to move down on the right. Motors take electricity and change it into motion.
51
What is a transformer?
A transformer is a device that changes the voltage of electricity (increases or decreases)
52
What are the two different types of transformers?
Transformers can be “step up” or “step down”, and, as the names imply, one increases voltage and the other decreases it.
53
What is a difference of step-up and step-down transformers?
If the number of coils on the input side of a transformer is higher than the number of coils on the output side, then the voltage will be decreased. (step-down transformer) If the number of coils is lower on the input side and higher on the output side then the voltage would increase. (step-up transformer)
54
What can be used to confirm a magnetic field was caused by an electric current?
A compass can be used to confirm a magnetic field was caused by an electric current. Because the compass needles align with the earth's magnetic field, they will change direction only if there is another magnetic field. So when there was an electric current, the compasses would not all be pointing toward the north, but changed direction because there is a new magnetic field created from the current.
55
What can an electromagnet do that a permanent magnet can not?
An electromagnet can strengthen its magnetic field by either increasing the current going through the solenoid, adding more loops to the solenoid, winding the coils closer together, or using a stronger ferromagnetic material. Permanent magnets cannot just increase their magnetic field strength like an electromagnet can.
56
Ex. of devices that use electromagnets
1. Cranes use strong electromagnets that can pick up and drop heavy objects by producing a current that attracts the objects, picking them up and then turns off the current to drop the objects off 2. Doorbells use electromagnets 3. Electromagnets are also used to record information on audiotapes, videotapes, computer hard drives, and credit cards
57
How is it that electricity and magnetism can make things move?
Magnets will either repel or attract each other, making them move, and electric currents produce a magnetic field.
58
What do magnetic fields do to a wire with a current traveling through it when that wire is placed in the magnetic field?
The wire would go in between the magnetic fields, the permanent magnet's magnetic field and the magnetic field produced by the current would interact. This would allow the wire to move down unless the magnetic field becomes reversed and then it would go up. The magnets would move the wire as if it were another magnet.
59
What sort of device would you need in order to confirm that a magnetic field is moving electrons in a wire?
A galvanometer would be used to measure the small currents going through the coiled wire (current strength) and the currents direction.
60
How does a galvanometer work?
A galvanometer has the electromagnet suspended and in between the opposite poles of two permanent magnets. The coiled wire is attached to the pointer and when current runs through the wire, it produces a magnetic field. The magnetic field created and the permanent magnets magnetic field interacts, causing the coiled wire and pointer to rotate. The galvanometer would then mark how much the pointer turns for a known current and if the current is unknown then the galvanometer can measure it.
61
What kind of energy transformations occur with motors?
Motors transform electrical energy into mechanical energy.
62
What parts make up a motor?
Armature ( usually has many wires looped around a ferromagnetic core, which strengthens the motor) Electromagnets are used instead of permanent magnets for larger motors A commutator (repeatedly reverses the flow of current and each end of it is attached to the armature so they rotate together) The commutator contacts the brushes which conduct the current, so by changing the brushes it reverses the current. This allows for the armature to spin continuously.
63
What kind of current is generated by a battery?
D.C. current is generated by a battery.
64
What parts make up a generator?
Slip rings (attached to end of armature) Armatures (a current is induced when it rotates) The brushes (current leaves generator through brushes) Crank (used to rotate the armature) this can also be a turbine in a very large generator that spins when water flows by it. If the generator is D.C. and not A.C., then instead of it having slip rings it would have a commutator.
65
What are the parts of a transformer?
Transformers have a primary coil (connected to circuit with voltage source and alternating current) and a secondary coil (connected to separate circuit with no voltage source).
66
How do transformers use induction?
Transformers take electricity that would first go throughout the primary coils and is then induced into the secondary coils so that the voltage is either increased (step-up) or decreased (step-down)
67
What are some uses of transformers?
Transformers are used to transmit electrical energy from generating plants to the consumer (like to your home or another building). Transformers are also used in fluorescent lights, televisions, X-ray machines, doorbells, electronic games, and portable CD players. You would use a step-up or step-down transformer depending on how many volts the device requires.
68
What does moving a wire through north and south magnetic fields do to the electrons in a wire?
Moving a wire through the north and south magnetic fields creates an electric current in the wire.
69
How do power plants use electric current?
Power Plants transmit the electric current, especially alternating current (its voltage can be raised or lowered so it is safe for everyday use) through wires to power schools, homes, and other various buildings.
70
What is a device called when it uses alternating magnetic fields to create a current?
Alternator, like a generator, but creates A.C. (alternating current)
71
Look at pictures in the HW's to see the different diagrams and look at the generator and motor parts!
72
Heating a magnet will....
decrease its strength
73
Who discovered that electricity could be generated from magnetism?
Michael Faraday
74
Generators can be made to create....
alternating or direct current
75
The magnetic poles of Earths magnetic field
constantly changing their position relative to Earths geographic poles
76
True or False: An electric generator is essentially the opposite of an electric motor.
True

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