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# mcat physics chapter 7 magnetism

## Terms

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in which direction is the magnetic field
in
electrostatics says that there are electric charges but in magnetism, there is no?
fundamental magnetic charge
magnetic fields are created by?
moving electric ch, currents in wires, and permanent magnets
magnetic fields exert forces on?
moving charges, currents in wires, and permanent magnets
B is a?
fixed and uniform magnetic field
si unit of magnetic field is?
Tesla
Testla=?
N(s)/m(C)
small magnetic fields are measured in?
gauss
1 tesla= __________ Gauss
10^4 gauss
a charge moves in a magnetic field
F from the magnetic field=?
F=qvBsinθ
F=qvBsinθ
what is B
the strength of the magnetic field
when a charge moves parallel or antiparallel to a magnetic field the magnetic force is?
zero
if a charge moves at θ=0 or 180 to a mag field what happens?
mag force is zero
F = qvB sinθ
what is θ?
θ is the smallest angle betw the vectors qv and B
F = qvB sinθ

what is q?
q is the charge of the moving particle
for determining direction of mag force
if q is nonzero and positive ch, then the vector qv _________ as v
points in the same direction
mag force
if q is nonzero and neg ch, then the vector qv _________ as v
points in opposite direction
ch in a magn field
if q or v is zero then the magnetic force?
is zero
the direct of the magn force will be ________ to the plane defined by qv and B
perpendicular
right handed rule for magn
the ________ of the right hand points in direction of the vector qv (if q is positive)
thumb
right h rule
the thumb of the right hand points in ?
direction of qv (if q is positive)
right handed rule
the thumb of rh points in dir of qv, and the fingers point in direct of?
of B
ch in magn field

right th points in dir of qv, fingers point in dir of B,
and _________ shows you direct of F
which way the palm faces
right handed rule for magn
thumb is?
fingers are?
palm is?
thumb is qv
fingers are B
palm is F- magn force on q
magn field
symbol x means?
a field going into the page.
x represents the tail end of an arrow going into the page
magn field
symbol  represents?
a field coming out of the page
it represents the tip of an arrow coming out of the page
Suppose a proton, whose charge is +1 .6 x 10-19 C, is moving with a speed of 15 m/s in a direction parallel to a uniform magnetic field of 3.0 T. What is the magnitude and direction
of the magnetic force on the proton?
since qv and B are parallel
the angle is 0 and the sin of 0 is 0 so
force is zero
F = qvB sin 0
Suppose a proton whose charge equals +1 .6 x 10-19 C is
moving with a speed of 15 m/s toward the top of the page
and through a uniform magnetic field of 3.0 T directed into
the page. What is the
direction of the magnetic force on the
the direction of the F is to the left
Remember the direction of the magnetic force on a negative charge is?
opposite the direction of the force on a positive charge moving in the same direct as the negat one
when a ch particle moves perpend to a const uniform magn field the resulting motion is?
circular motion w a const speed in a plane perpend to mag field
charg part mov perp to magn field
the centripetal force is the?
magnetic force
F=qvBsin90 (sin90 is 1)
charg part mov perp to magn field
F=qvB= ?
F=qvB=mv^2/r
ch part in a magn field

F=qvB=mv^2/r
you can use this to solve for what?
orbit radius, mang field, etc

r=mv/qB B=mv/qr
Suppose the proton of the previous example is allowed to
circle (counterclockwise) in the same perpendicular magnet-
ic field of 3.0 T with the same speed of 15 m/s. What is the orbit radius r? (The mass of a proton is
1.67 x 10-27 kg.)
r=mv/qB
for a given field direction, if positive charges circle clockwise, then negative charges circle?
counterclockwise
electric current
when 2 points at different __________are connected w a conductor, charge flows betw the 2 points
electric potentials
magnitude of current is?
the amount of charge i=Î”q/Î”t
current is in the directions that?
positive ch would flow
t or f
current is in the direct that posit ch would flow
t
si unit of current is?
ampere
ampere is the si unit of?
current
1A= ?
1 coulomb/second
1 c/s=
1 A
since electrons are negativ cha they go from _________ potent to ___________ potent
low to high potential
by convent direc of current is direct posit ch would flow which is from ________ potent to __________ potent
high to low
force on current carrying wire due to magn field
F=?
F=iLBsinθ
force on current carrying wire due to magn field

iLBsinθ is equal to what?
the F due to the magnetic field
right hand rule for force on a current carrying wire in a magn field

thumb of rh points in?
DIRECTION of current i
right hand rule for force on a current carrying wire in a magn field

fingers of rh point in?
direction of B
right hand rule for force on a current carrying wire in a magn field

right hand rule
thumb?
fingers?
palm?
thumb- direct of i
fingers- direct of B
palm- F - the magn force on current carrying wire
Suppose a wire of length 2.0 m is conducting a current of 5.0 A toward the top of the page and through a 30 Gauss uni-
form magnetic field directed into the page. What is the direction of the magnet-
ic force on the wire?
force on wire is to the left
Suppose a wire of length 2.0 m is conducting a current of 5.0
A toward the top of the page and through a 30 Gauss uni-
form magnetic field directed into the page (see figure
7.3(a)). What is the magnitude and direction of the magnet-
to convert gauss into tesla

1 T= 10^4 Gauss
10^4 Gauss= __________ Tesla
10^4 Gauss= 1 Tesla
if a wire has no current moves thr a magnetic field what happens?
nothing. wires w no curr are electric neutral. no magn force is generated
Suppose a wire of length 2.0 m is conducting a current of 5.0
A toward the top of the page and through a 30 Gauss uni-
form magnetic field directed into the page. What is the magnitude and direction of the magnet-
ic force on the wire?
F = iLB sinθ = iLB

=5.0(2.0)(3.0)X 10-3)
any moving charge creates a?
magnetic field
differ ways to gener a magn field?
1. flow of ch in perman magn
2. electric curr
3. indiv moving ch
it is the _____________ that gives rise to the magnetic field
movement of ch
magnetic field lines

magnetic field is ____ to the magn field line at any point
tangent
_____________ can be used to visualize the magnetic field
magnetic field lines
magn materials are classified as?
1. diamagnetic
2. paramagnetic
3. ferromagnetic
diamagnetic material are?
indiv atoms have no net magn field. will be repelled from pole of a strong bar magn. called weakly antimagnetic
which magnetic material is weakly antimagnetic?
diamagnetic
in a ______________ the individ atoms have no net magn field
diamagnetic material
paramag material is _____________ magnetic
weakly
in paramag and ferromagnetic mat the indiv atoms do have a ?
net magn field but they are randomly oriented so net magn field.
ferromagnetic materials below the critical temperature called _______ can dev a higly aligned magn field
Curie temperature
above the Curie temp the ferromagnetic material is ?
paramagnetic
_________ are called strongly magnetic
ferromagn
t or f
iron, nickel, and cobalt are ferromagnetic
t
when the north pole of a compass magnet points along local field lines of earths mag field it is pointing?
towards a magnetic south pole
on earth, what we call the northern direction is really?
the direction of a magn south pole
what is the name of the critical temp below which a paramagn mater bec ferromagn?
curie temperat
north pole is place where magnetic field lines?
emerge
south pole is where magn field lines?
enter
the _________ pole is where magnetic field lines emerge
north
the _______________ pole is where magnetic field lines enter
south
t or f
a current carrying wire will prod a magnetic field in its vicinity
t
the mag f of a curr carrying wire is the _______ of the magn f due to indiv moving ch of the curr
vector sum
an infinitely long str wire w curr

B=
B= µoi/2Ϭr
µo is
the permeability of free space
= 4Ï€ X 10-â· Teslaâˆ™meter/ampere
what are the units of µo?
Teslaâˆ™meter/ampere
µo=
=4Ï€ X 10-â· Teslaâˆ™meter/ampere
=1.26 X 10-6 Tâˆ™m/A
for a long str wire the magn field strenght __________ with distance
drops off
magnetic field lines __________ currents
encircle
current carrying wire
right hand rule
right thumb is?
fingers?
right thumb is in direct of current
fingers curl in direction of generated mag field B
A straight wire carries a current of 5 A toward the top of the
page. What is the direc-
tion of the magnetic field at point P, which is 10 cm to the
left of the wire?
B is coming out of the page.
magn field at the center of a circular loop of curr carrying wire of radius r is?
B=µoi/2r
B=µoi/2r
only gives the magnetic field at?
one point in space, the point at the center of the loop
Suppose a wire is formed into a loop that carries current
clockwise (that is, electrons flow counterclockwise) Find the direction of the magnetic field pro-
duced by this loop:
a. within the loop.
b. outside of the loop.
a. into the page
b. outside the loop. B will point out of the page.

A negative charge placed in an external magnetic field circulates
counterclockwise in the plane of the paper as shown below. In which
direction is the magnetic field pointing
out of the page

If, as in the accompanying figure, an electron is travelling straight
out of the page crossing a magnetic field that is directed from left to
right, in which direction will t
downward, dont forget its an electron so its opposite.

A long straight wire carrying current I is placed between the poles of
a horseshoe magnet as shown in the figure below. Does the force on
the wire depend on the width of the
yes, F=iLB so the wider the pole face, the more wire that is in the magnetic field and the force can be stronger
A positively charged particle enters a region with a uniform electric
field, as shown, and is initially moving perpendicular to the field. In
what direction must a uniform magnetic field be oriented so that the
net force on the particle is

heading out of the page, it will creat a magnetic force F=qvBsin angle downwards, electric field is creating a force pushing the charge up

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