Download Magnetism Review

Forces 10.0 - Magnetism Review
Name: ___________________
Conceptual Questions
1. What happens when you break a bar magnet in half? Explain.
Two complete magnets are created. It is not possible to separate a north pole from a south pole, so
continued breaking of magnets would create more and more complete magnets.
2. Where do magnetic field lines begin? Where do they end? Explain.
Magnetic field lines are continuous and so have no beginning and no end. They continue through the
inside of a magnet or through the empty core of a solenoid
3. An unmagnetized nail will not attract an unmagnetized paper clip. However, if one end of the nail is in
contact with a magnet, the other end will attract a paper clip. Explain.
The magnetic domains inside of the nail are, in isolation, randomly oriented. As a result, the nail
exhibits no magnetic properties or behaviour. However, when placed near (or in contact with) a
magnet, the nail’s domains will orient themselves with the magnetic field of the magnet, turning into
a magnet itself (it is able to do this because its domains are not rigid). As a magnet, the nail will now
attract the paper clip.
4. A student has placed two cylindrical permanent magnets on a rod as shown. If
she adds another identical magnet on the top with the same orientation, the
space between the magnets will
a) increase because the magnetic force has doubled.
b) decrease because the gravitational force has doubled.
c) stay the same because both forces have doubled.
d) decrease because the gravitational force increased more than the magnetic.
e) increase because the magnetic force increased more than the gravitational.
The third magnet will attract and stick to the magnet at the top, so their
masses will combine and the gravitational force will double. However, because the added magnet is
further away from the bottom magnet than the one it has stuck to, the magnetic repulsion force will
still increase, but not double.
5. A hiker is standing directly east of a vertical pole, holding a magnetic compass, as
shown. The compass is pointing north. Unknown to the hiker, a strong flow of
electrons is turned on such that the electrons flow upwards through a conductor
embedded in the pole. What happens to the compass needle?
a) The needle continues to point north.
b) The needle swings to point south.
c) The needle swings to point west, towards the pole.
d) The needle swings to point east, away from the pole.
As dictated by left-hand rule #1 (linear current-carrying conductors) for electron flow.
6. Two parallel wires are carrying electrical current flowing in the same direction. These wires will tend
a) to repel each other.
b) to exert no force on each other.
c) to spin along their long axis.
d) to attract each other.
e) to twist at right angles to each other.
F
F
Likewise for the
other wire
Forces 10.0 - Magnetism Review
Name: ___________________
Problems
7. Six magnets slide easily on a track, and settle into the arrangement shown in the diagram. The south
pole of one magnet is labelled (S). Identify the identified poles below as either north or south.
A __ N ___
D __ N ___
B __ N ___
E __ S ___
C __ S ___
8. Sketch the total magnetic field produced by the three magnets below
9. Sketch the magnetic field produced by each of the following current-carrying conductors below.
a)
b)
c)
I
10. An electric current is travelling southward in a straight, horizontal conductor. State the direction of the
magnetic field
Below the conductor ___ east _____
Above the conductor ____ west ____
East of the conductor ___ up _______
West of the conductor ___ down _____
11. Identify each end of the solenoids below as either N or S and sketch their magnetic fields.
a)
b)
c)
N
S
I
I
N
I
S
N
S
Forces 10.0 - Magnetism Review
Name: ___________________
12. Indicate the direction of the current for each end of the solenoids below.
a)
b)
I
c)
S
N
I
N
I
13. Indicate the direction of the force on the current-carrying conductor(s) below.
a)
b)
c)
B
F
F
N
I
S
F
F
F
F
14. Indicate the
a) direction of the current
15.
B
I
b) poles of the magnet
c) direction of B
S
I F
F
F
B
N
S
e- flow
16. An electron, travelling east, enters a magnetic field which is directed upwards. Sketch the situation
below as well as the direction the electron will be deflected as it enters the magnetic field.
N
N
B
e-
B
ee- direction is north
e- direction is north
Forces 10.0 - Magnetism Review
Name: ___________________
17. Three particles, a, b and c enter the magnetic field below. What can you say about the charge of each
particle?
a
a, b, c
a is positive
b is neutral
c is negative
b
c