Physics 360 Exam 2

Are our houses wired in series or in parallel?

in parallel

why are houses wired in parallel?

to make sure that if one branch stops working, the entire house doesn’t lose power

the equation for the equivalent resistance of resistors in parallel is the top or bottom one?

bottom

the equation for the equivalent resistance of resistors in series is the top or bottom one?

top

in a series, what is the same for all?

current

junctions are…

point where 3 or more devices are connected

junctions alway occur in…

pairs

power branch =

branch with power source

branches that are connected in parallel are _____ from each other.

independent

each branch in parallel makes its own…

single loop with the power source

T/F. Current in parallel branches is different.

True, it depends on the devices in each branch

what is the same for branches in parallel?

voltage

branch

segments that carry different current

junctions split circuit into _____.

branches

the highest current is that which is in the ___ ___.

power branch

the currents of all devices must…

add up to current of power source

resistance and current have a ___ relationship

inverse

in parallel, the device with the lowest resistance will get the _____ part of the total current.

largest

in parallel, the device with the highest resistance will get the ____ part of the total current.

smallest

at a junction, all current that enters must also

leave

the more branches added to a voltage source the…

higher the current will be in the source

what is the disadvantage of adding too many branches to a voltage source in parallel?

the higher the current, the more heat will be produced which can damage the source

the more branches connected in parallel, the lower the…

equivalent resistance

in a simple single loop, there is one ___ and one ____.

device, battery

a multi loop circuit has one ___ and multiple ____.

source, branches

an image is everything you see in a ____/____ ____

mirror/reflective surface

the branch that has the highest power has the lowest ____

resistance

how do we know that our houses are in parallel and not in series?

when we turn one thing off, everything else does not turn off

what is the function of a cfircuit breaker?

detects power surges and stops flow of electricity before damage is done

why is it not a good idea to produce an overload anywhere in our homes?

can cause fire

in our homes what is the voltage that we receive? (how many volts)

120 V

do we get AC or DC voltage in our homes?

AC

lodestones are rocks that…

always pointed in the same direction

how were lodestones used?

for navigation

metals that exhibit strong magnetic effects are called _____.

ferromagnets

ferromagnetic materials respond strongly to magnets and can also be…

magnetized

ambient magnetization

magnetization process done by long exposure to earth’s magnetism

a metal is ferromagnetic if it can be…

magnetized

the atoms of Fe, Co, and Ni are _____ ______

natural magnet

each natural magnet atom has what two things?

a north and south pole

magnetic dipoles can be found in natural magnet atoms and have ____ _____

magnetic dipole

magnetic dipole vector is drawn from…

south to north

when two atoms are near each other, what happens?

their magnetic dipoles are forced into similar direction

material can be magnetic while also not being a ____

magnet

magnetic domain

region where magnetic dipoles align

in a regular piece of Fe, there can be domains, but that does not mean that the piece of Fe is a magnet. T/F

true

what is the law of poles

opposites attract and like repels

monopoles

singular atom that has only a north or south pole

are magnetic monopoles real?

we do not know since they have never been observed

magnetic force units

newtons, N

magnetic field unit

T

tesla in standard unit

N/(C*m/s)

electric field si units

V/m or N/C

electricity letter sign

E

magnetism letter sign

B

the source of electric fields are … while the source of magnetic fields are…

charges, electric current

what is an electric current?

charge in motion

what is the difference between electric and magentic field sources?

electric field source is a stationary charge while magnetic field source is a charge in motion

magnets are able to attract materials by first doing what to them?

polarizing them

what is the magnetic flux?

the total magnetic field that passes through a given area

what is the normal vector?

vector that goes out from the face of the coil

T/F. The face of a coil is specific and not arbitrarily decided.

F

for there to be magnetic flux, the coil or wire must be placed where?

in an external magnetic field

the maximum flux occurs when the magnetic field vector is _____ to the normal vector.

parallel

flux is 0 when the magnetic field vector is ___ to the normal vector.

perpendicular

at what angle is the flux going to be 0?

90 degrees

at what angle between the normal vector and magnetic field is the flux the maximum and also positive?

0

at what angle between the magnetic field and normal vector is the flux negative and at its’ max?

180 degrees

when the field lines cross from the back to the front, what happens to the flux?

it is positive

when field lines cross from front to back, what happens to the flux?

it is negative

what was oersted’s accidental discovery?

electric currents are sources of magnetic fields

a charged particle in a magnetic can receive a magnetic force if the charge has ____.

velocity

a charged particle in a magnetic field can receive a magnetic force if the velocity it has is…

perpendicular or partially perpendicular to the magnetic field

T/F.only the part of a coil/wire that is exposed to the external magnetic field receives a magnetic force.

T

magnetic force cannot change the ____ of a particle.

speed

magnetic force can change the ____ of a particle.

direction

when is a magnetic force centripetal?

constant velocity

what equation is used when velocity is constant to calculate the magnetic force?

(mass times squared velocity)/radius

right hand rule 1 is used to find what?

direction of magnetic force

how do you do right hand rule 1?

put thumb in direction of velocity and four fingers in the direction of magnetic field. bend four fingers inwards and that is the magnetic force direction

the right hand rule 1 applies to what kind of particle?

positive

what do you do if the particle is not positive?

use rule and do opposite direction of what you get

For these equations, what angle(s) produces no force?

0 and 180 degrees

for these two equations, what angle produces maximum force?

90 degrees or 270 degrees

the greek letter mu with a vector sign on top of it is called what?

magnetic dipole

how is the magnetic dipole directed?

points towards N side of a magnet along magnet axis

the orbital motion of an electron is also a ___ _______.

tiny current

the magnetic dipole with a small subscript that says spin refers to what?

the electron spin that contributes to the magnetic dipole

the magnetic dipole sign(greek mu) with the subscript orbital refers to what?

the orbital motion of the electron that contributes to the magnetic dipole

what contributes more to the magnetic dipole, electron spin or orbital motion of the electron?

electron spin

if the net magnetic dipole is not equal to 0, what does this mean about the atom?

the atom itself is a magnet

for most atoms, the net magnetic dipole is…

0

why is the net magnetic dipole for most atoms 0?

electron spin pairs cancel out

only three atoms show clear N and S at room temperature, what are they?

iron, cobalt, nickel

Fe, Co, and Ni are the three main ferromagnetic metals that show…

magnetic properties at room temp

diamagnetic

not magnetic at all

paramagnetic

develops N and S poles when placed in external magnetic field

T/F. paramagnetic materials retain the N and S poles when removed from the magnetic field.

F, they lose the poles when they leave the magnetic field

ferromagnetic materials

develop N and S poles when placed in magnetic field

T/F. ferromagnetic fields retain north and south poles when removed from magnetic field.

T