Reflection and Refraction > Electromagnets Flashcards
Based from the Magnetism Lab Sheet, what do you notice about the interaction of the bar magnets you were given?
the iron filings are attracted to the south pole of the magnet
Based from the Magnetism Lab Sheet, why did the iron filings behave that way?
the iron filings are more attracted to the southern pole of the magnet
what a material contains when it has the ability to exert forces on magnets or other magnetic materials
magnetic force
a material that keeps its magnetic properties even when it is not close to other magnets
permanent magnet
magnets have ? poles
two opposite
poles of a magnet
north
south
the ends of a magnet
poles
Magnetic forces depend on the ——— of the poles
alignment
magnets exert —— on each other
forces
virtually transparent to magnetic forces
insulating materials (wood, plastic, etc.)
conducting materials (aluminum, etc.) also allow magnetic forces to pass through, but may —— the forces
change
the strength of the force between magnets depends on the ——– between them
distance
magnetic force ——— with distance much faster than does either gravity or the electric force
decreases
two basic types of magnets
natural
artificial
all magnets create a ——– —– in the space around them, and the ——– —– creates forces on other magnets
magnetic field
the field of influence that a magnet creates around it
magnetic field
a black metallic ore that has strong magnetic property
lodestone
the number of field lines in a certain area indicates the relative ——— of the magnetic field in that area
strength
the arrows on the field lines indicate the ——— of the force
direction
the —— the lines are together; the ——- the field
closer; stronger
magnetic field lines ALWAYS point —- from a magnet’s north pole and —— its south pole
away; toward
sources of nearly all magnetic effects in matter
electrons in atoms
two ways in which electrons create magnetism
- electrons around the nucleus and their motion makes the entire atom a small magnet
- electrons themselves act as though they were magnets
ALL atoms have electrons, but there is a great ———– in the magnetic properties of materials
variability
electrons in some atoms —– to cancel out one another’s magnetic influence
align
a property of a material when its electrons are oriented so their individual magnetic fields CANCEL each other out [slightly repelled]
diamagnetic
a property of a material when its individual atoms are magnetic but the atoms themselves are randomly arranged so the OVERALL magnetism of a sample is zero
paramagnetic
a material that has very strong magnetic properties
ferromagnetic
examples of ferromagnetic materials
iron nickel cobalt gadolinium dysprosium
a group of atoms with similar alignment or orientation towards a magnet
magnetic domain
examples of diamagnetic materials
antimony zinc copper gold silver table salt mercury alcohol water hydrogen air argon
examples of paramagnetic materials
aluminum chromium alkali metals platinum oxygen wood
magnetic domains in a ferromagnetic material will always orient themselves to attract a ——— magnet
permanent
if a —– pole approaches, domains grow that have south poles facing out
north
if a —– pole approaches, domains grow that have north poles facing out
south
materials that make good permanent magnets
hard magnets
a common and inexpensive material, which contains iron and carbon, used to create hard magnets
steel
materials that lose their magnetism quickly
soft magnets
By 1200, Italian explorers were using a ——- to guide ocean voyages beyond the sight of land
compass
when using a compass, the north-pointing end of a needle points toward a spot near the Earth’s geographic —– pole
north
the Earth’s magnetic poles are defined by the planet’s magnetic —–
field
the —– magnetic pole of the planet is near the north geographic pole
south
natural force that causes magnets to attract other particles
magnetic force or magnetism
it will pull some metals toward itself
magnet
what is the rule of magnetism?
it is a force of attraction or repulsion that acts at a distance between various substances
What happens to the two poles if you break a magnet in half?
the fragment with N pole will have an S pole and vice versa
“the poles adjust”
the —- of a magnet are where the magnetic force is the strongest
ends
magnetic field lines leave the —– end of a magnet and enter the —– end of a magnet
north; south
region where the magnetic forces act
magnetic field
The Earth behaves as if there was a —— in its interior
magnet
a compass will always point towards the —–
North
magnetized piece of metal that can spin
compass
a compass —— to a magnetic field from a magnet
reacts
discovered the deflection of a compass needle while performing a demonstration for his students
Hans Christian Oersted
discovered the fundamental connection between electricity and magnetism
[electricity = magnetism]
Hans Christian Oersted
what happens to a wire when it carries electricity?
a current-carrying wire becomes a magnet by setting up a magnetic field around it
what is your proof for this: “current-carrying wire becomes a magnet by setting up a magnetic field around it”?
deflection of the compass needle
according to Oersted’s experiment, when current is present, the needle deflects ————- to the wire
perpendicular
according to Oersted’s experiment, when current is reversed, the needle deflects in the ——— direction
opposite
Hans Christian Oersted’s principle
“a charge moving through a straight conductor produces a circular magnetic field around it”
remember!
electric current from + to the - terminal of the battery
RIGHT HAND GRIP RULE
what happens to the magnetic field around the wire if we flip the direction of current?
the magnetic field around the wire changes direction when the flow of current changes
what is your proof for this: “the magnetic field around the wire changes direction when the flow of current changes”?
the flipping of the compass needle to the other direction
if the current through the wire increases, the strength of the induced magnetic field ——–
increases
a long coil of several turns of wire
solenoid
the magnetic field inside a solenoid is ——– than the magnetic field outside it
stronger
the concept of solenoid led to the creation of a simple ————-
electromagnet
devices that create a magnetic field through the application of electricity
electromagnet
if the number of coils in a wire increases, the strength of the induced magnetic field ———
increases
tubular coil of wire with many turns
solenoid
a temporary magnet made by passing electric current through a wire coiled around an iron bar
electromagnet
consists of an iron core placed inside a wire coil
electromagnet
uses of electromagnets
doorbells could send spacecraft deep into space pick up and drop junked cars trains (maglev, bullet, etc.) loudspeakers (consist of permanent magnet surrounding an electromagnet)
invented electric motor, generator and transformers
Michael Faraday
discovered electromagnetic induction
[magnetism = electricity]
Michael Faraday
Michael Faraday’s conclusions
an electrical current is produced by constantly changing the magnetic field
converts mechanical energy to electrical energy
generator
current that flows in one direction
direct current (DC)
current that flows in a back-and-forth manner
alternating current (AC)
converts electrical energy to mechanical energy
motor
a current coming out of the plane will have its magnetic field turning:
a. counter clockwise
b. clockwise
a. counter clockwise
when ———— materials are placed in a magnetic field, the atoms align so that the material has a weak magnetic force
paramagnetic
symbol used to denote the direction of a current into the plane
(.) and (x)
bending of a wave as it passes through different media
refraction
why is an iron core needed in an electromagnet?
an iron core is necessary to make the magnet stronger
how are electromagnets different to either temporary or permanent magnets?
an electromagnet can be turned on and off
to increase the magnetic field of an electromagnet, use a more powerful ——-
battery
type of wire (based from the web quest)
the copper wire attracts the most number of filings
thickness of the wire (based from the web quest)
the thicker the wire, the more iron filings are attracted
AC or DC power supply (based from the web quest)
DC power supply attracts more iron filings
voltage (based from the web quest)
the higher the voltage, the more iron filings are attracted
number of winds [turns] in the wire (based from the web quest)
the more number of winds, the more iron filings are attracted
describe how an electric bell works
- when the current flows through the circuit, the electromagnet makes a magnetic field
- the electromagnet attracts the springy metal arm
- the arm hits the gong, which makes a sound
how is a magnet used inside of a simple AC generator
- a wire passing through a magnetic field causes electrons in that wire to move together in one direction
- a steam engine or some other outside source of motion moves the wire or armature through the magnetic field created by the magnets
- the loop is spinning; which means that the flow of electrons keeps changing!
ferromagnetic materials have —- unpaired electrons than paramagnetic materials
more
if an electromagnet has a high voltage, then its magnetic capability ———
increases
change in magnetic flux
electromagnetic induction
generates electricity by manipulating the magnetic field within an area
electromagnetic induction
Between two upright circles, (a) bigger (b) smaller, which will contain more magnetic flux?
(a) bigger
Between (a) an upright circle and (b) a horizontal circle, (a) will contain —- magnetic flux
more
more perpendicular, —— magnetic flux
higher
- the product of the average magnetic field times the perpendicular area that it penetrates
- quantity of convenience in the statement of Faraday’s Law and in the discussion of objects like transformers and solenoids
Magnetic flux
- (often denoted Φ or ΦB) through a surface
- its SI unit is the weber (Wb) (in derived units: volt-seconds)
magnetic flux
describe how the appearance of a pencil point changes as it moves closer the concave side of the spoon
the image slowly becomes upright and the size magnifies
describe how the appearance of a pencil point changes as it moves closer the convex side of the spoon
the orientation of the pencil point is still upright however the size reduces
describe the appearance of the coin if you were able to see it with the water in the cup (clear, plastic)
We were able to see it since we came from low N to high N. The image appears more shallow and visible.
why did the spoon appear to be “broken” inside that cup?
it appeared broken because of the change in density
what happened to the letters of the newspaper when water droplets were placed on the plastic wrap?
letters were magnified
water droplets act as a lens
what happened to the letters of the newspaper when the plastic wrap is folded in half?
image’s magnification appeared the same as the actual text
image was blurry
the smaller the droplet, the —- the magnification
more
——– ——- in compasses are used in navigations
magnetic needles
As charges move (such as in an electric current), ——— can be induced
magnetism
historians believed that they were the first to build compasses to help them navigate the seas
Chinese
Greek philosopher associated with “magnets” and also the first to observe its property
Thales
it was given the name “——” after Magnesia, a district in the Asia Minor
magnet
Another tale about magnets was based on the story of a shepherd named ——
Magnes
attracts alloys
magnets
not able to retain their magnetic ability after losing contact with a magnet
paramagnetic materials
artificial magnets are made through ——- ———
induced magnetism
types of artificial magnets
permanent
temporary
magnets made of pure and soft iron
temporary magnets
