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ConcepTest PowerPoints
Chapter 20
Physics: Principles with
Applications, 6th edition
Giancoli
© 2005 Pearson Prentice Hall
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ConcepTest 20.1a Magnetic Force I
1) A positive charge enters a
1) out of the page
uniform magnetic field as
shown. What is the direction
of the magnetic force?
2) into the page
3) downwards
4) to the right
5) to the left
x x x x x x
v
x x x x x x
x x x xq x x
ConcepTest 20.1b Magnetic Force II
2) A positive charge enters a
1) out of the page
uniform magnetic field as
shown. What is the direction
of the magnetic force?
2) into the page
3) downwards
4) upwards
5) to the left
x x x x x x
x x x x vx x
q
x x x x x x
ConcepTest 20.1c Magnetic Force III
3) A positive charge enters a
1) out of the page
uniform magnetic field as
shown. What is the direction
of the magnetic force?
2) into the page
3) zero
4) to the right
5) to the left


v

q

ConcepTest 20.1d Magnetic Force IV
4) A positive charge enters a
1) out of the page
uniform magnetic field as
shown. What is the direction
of the magnetic force?
2) into the page
3) zero
4) to the right
5) to the left
v
q
ConcepTest 20.2 Atomic Beams
5) A beam of atoms
x x x x x x x x x 1x x x
enters a magnetic field
x x x x x x x x x x x x
region. What path will
x x x x x x x x x x x x
the atoms follow?
x x x x x x x x x x x x
x x x x x x x x x x x x
4
x x x x x x x x x x x x
2
3
ConcepTest 20.3 Magnetic Field
6) A proton beam enters into a
magnetic field region as shown
below. What is the direction of
the magnetic field B?
1) + y
2) – y
3) + x
4) + z (out of page)
5) – z (into page)
y
x
ConcepTest 20.4a Mass Spectrometer I
x x x x x x x x x x x x
7) Two particles of the same
x x x x x x x x x x x x
mass enter a magnetic field with
the same speed and follow the
paths shown. Which particle
has the bigger charge?
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
1
2
3) both charges are equal
4) impossible to tell from the picture
ConcepTest 20.4b Mass Spectrometer II
8) A proton enters a
1) it increases
uniform magnetic field
that is perpendicular to
the proton’s velocity.
What happens to the
kinetic energy of the
proton?
2) it decreases
3) it stays the same
4) depends on the velocity direction
5) depends on the B field direction
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
ConcepTest 20.5 Velocity Selector
9) What direction would a B field
1) up (parallel to E )
have to point for a beam of
electrons moving to the right to
go undeflected through a region
where there is a uniform electric
field pointing vertically upward?
2) down (antiparallel to E )
3) into the page
4) out of the page
5) impossible to accomplish
E
B=?
electrons
v
ConcepTest 20.6a Magnetic Force on a Wire I
1) left
10) A horizontal wire carries a
2) right
current and is in a vertical
3) zero
magnetic field. What is the
4) into the page
direction of the force on the wire?
5) out of the page
I
B
ConcepTest 20.6b Magnetic Force on a Wire II
1) left
11) A horizontal wire carries a
2) right
current and is in a vertical
3) zero
magnetic field. What is the
4) into the page
direction of the force on the wire?
5) out of the page
I
B
ConcepTest 20.7a Magnetic Force on a Loop I
1) + x
12) A rectangular current
2) + y
loop is in a uniform magnetic
3) zero
field. What is the direction of
4) - x
the net force on the loop?
5) - y
B
z
y
x
ConcepTest 20.7b Magnetic Force on a Loop II
1) move up
13) If there is a current
2) move down
in the loop in the
3) rotate clockwise
direction shown, the
4) rotate counterclockwise
loop will:
5) both rotate and move
B field out of North
B field into South
N
S
N
S
ConcepTest 20.8a Magnetic Field of a Wire I
14) If the currents in these wires
1) direction 1
have the same magnitude, but
2) direction 2
3) direction 3
opposite directions, what is the
4) direction 4
direction of the magnetic field at
5) the B field is zero
point P?
1
P
4
2
3
ConcepTest 20.8b Magnetic Field of a Wire II
15) Each of the wires in the
figures below carry the same
current, either into or out of the
page. In which case is the
magnetic field at the center of
the square greatest?
1
B=?
2
B=?
1) arrangement 1
2) arrangement 2
3) arrangement 3
4) same for all
3
B=?
ConcepTest 20.9a Field and Force I
16) A positive charge moves
1) + z (out of page)
parallel to a wire. If a current is
2) - z (into page)
suddenly turned on, which
3) + x
direction will the force act?
4) - x
5) - y
y
+q
x
z
I
ConcepTest 20.9b Field and Force II
17) Two straight wires run parallel
to each other, each carrying a
current in the direction shown
below. The two wires experience
a force in which direction?
1) toward each other
2) away from each other
3) there is no force
ConcepTest 20.10 Current Loop
1) left
18) What is the direction of
2) right
the magnetic field at the
3) zero
center (point P) of the
4) into the page
square loop of current?
5) out of the page
I
P