1.
An electron passes the north pole of a bar magnet as shown below.
What is the direction of the magnetic force on the electron?
A.
Into the page
B.
Out of the page
C.
To the left
D.
To the right
(Total 1 mark)
2.
The definition of the ampere refers to the
A.
number of electrons passing a given point per second.
B.
force between parallel current-carrying conductors.
C.
power dissipated per unit resistance.
D.
amount of charge transferred per second.
(Total 1 mark)
3.
A long straight wire carries an electric current perpendicularly out of the paper. Which of the
following represents the magnetic field pattern due to the current?
(Total 1 mark)
IB Questionbank Physics
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4.
An electron travelling in the direction shown by the arrow X, enters a region of uniform
magnetic field. It leaves the region of field in the direction shown by the arrow Y.
The direction of the magnetic field is
A.
in the direction of X.
B.
into the plane of the paper.
C.
in the opposite direction to X.
D.
out of the plane of the paper.
(Total 1 mark)
IB Questionbank Physics
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5.
A particle, of mass m and charge q, moves with velocity v perpendicularly to a magnetic field.
The magnitude of the magnetic force acting on the particle at a particular point is F. Which of
the following gives the magnitude of the magnetic field strength at that point?
A.
F
q
B.
F
m
C.
D.
F
ν
F
qν
(Total 1 mark)
6.
A current is established in a coil of wire in the direction shown.
The direction of the magnetic field at point P is
A.
out of the plane of the paper.
B.
into the plane of the paper.
C.
to the left.
D.
to the right.
(Total 1 mark)
IB Questionbank Physics
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7.
A point mass carries a positive charge +Q and is at rest in a magnetic field. The field is in the
direction shown.
The magnetic force acting on the charge is
A.
from left to right in the plane of the page.
B.
from top to bottom in the plane of the page.
C.
into the plane of the page.
D.
zero.
(Total 1 mark)
IB Questionbank Physics
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8.
A current carrying wire is in the same plane as a uniform magnetic field. The angle between the
wire and the magnetic field is θ.
The magnetic force on the current carrying wire is
A.
zero.
B.
into the plane of the paper.
C.
out of the plane of the paper.
D.
at an angle θ to the direction of the magnetic field.
(Total 1 mark)
IB Questionbank Physics
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9.
In the diagram, a long current-carrying wire is normal to the plane of the paper. The current in
the wire
is directed into the plane of the paper.
Which of the arrows gives the direction of the magnetic field at point P?
A.
W
B.
X
C.
Y
D.
Z
(Total 1 mark)
IB Questionbank Physics
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10.
A positively charged particle enters the space between two charged conducting plates, with a
constant velocity directed parallel to the plates, as shown.
The top plate is positively charged and the bottom plate is negatively charged. There is a
magnetic field in the shaded region PQRS. The particle continues to move in a horizontal
straight line between the plates. Which of the following correctly describes the magnetic field
direction?
A.
Into plane of paper
B.
Out of plane of paper
C.
Up
D.
Down
(Total 1 mark)
IB Questionbank Physics
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11.
An electron is moving in air at right angles to a uniform magnetic field. The diagram below
shows the path of the electron. The electron is slowing down.
Which of the following correctly gives the direction of motion of the electron and the direction
of the magnetic field?
Direction of motion
Direction of magnetic field
A.
clockwise
into plane of paper
B.
clockwise
out of plane of paper
C.
anti-clockwise
into plane of paper
D.
anti-clockwise
out of plane of paper
(Total 1 mark)
12.
This question is about force fields.
(a)
Outline what is meant by a field of force.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
IB Questionbank Physics
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(b)
Five particles A to E are each placed in a different type of field. Complete the table to
identify the nature of the field in which each particle is situated.
Particle
Charge on
particle
Initial direction of
motion of particle
Direction of
force on particle
A
uncharged
stationary
in direction of
field
.....................................
B
negative
along direction of
field
opposite to
direction of field
.....................................
C
positive
normal to direction
of field
normal to
direction of field
.....................................
D
positive
normal to direction
of field
in direction of
field
.....................................
E
uncharged
opposite to direction
of field
in direction of
field
.....................................
Type of field
(5)
(Total 7 marks)
13.
This question is about motion in a magnetic field.
An electron, that has been accelerated from rest by a potential difference of 250 V, enters a
region of magnetic field of strength 0.12 T that is directed into the plane of the page.
IB Questionbank Physics
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(a)
The electron’s path while in the region of magnetic field is a quarter circle. Show that the
(i)
speed of the electron after acceleration is 9.4 × 106 m s–1.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(ii)
radius of the path is 4.5 × 10–4 m.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(b)
The diagram below shows the momentum of the electron as it enters and leaves the
region of magnetic field. The magnitude of the initial momentum and of the final
momentum is 8.6 × 10–24 N s.
(i)
On the diagram above, draw an arrow to indicate the vector representing the
change in the momentum of the electron.
(1)
IB Questionbank Physics
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(ii)
Show that the magnitude of the change in the momentum of the electron is
1.2 × 10–23 Ns.
...........................................................................................................................
...........................................................................................................................
(1)
(iii)
The time the electron spends in the region of magnetic field is 7.4 × 10–11 s.
Estimate the magnitude of the average force on the electron.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
(Total 7 marks)
IB Questionbank Physics
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