Review: Magnetic Fields and Electromagnetic Induction

1
Review Magnetic Fields and Electromagnetic
Induction

• Physics Chapters 24 25

2
True or False Magnetic field lines form closed
loops. Answer True
3
Which of these materials are used to make
permanent magnets a) neodymium b) gadolinium
c) ALNICO V d) all of the above Answer d
4
True or false Electromagnets are useful because
they can easily be turned on and
off. Answer T
5
True or False When a magnet is allowed to swing
freely, it comes to rest aligned in the
north-south direction. Answer True
6
True or false In a motor, mechanical energy is
used to produce electric current. Answer
F - generator
7
A small magnet mounted so it is free to
turn a) galvanometer b) compass Answer b
8
True or False Hans Christian Oersted discovered
that electric current creates a magnetic
field. Answer True
9
True or false The iron core is included in an
electromagnet because it is a good
conductor. Answer F the iron core is
included because it is easily magnetized and
thereby enhances the magnetic field of the coil.
10
True or False Increasing the current in a wire
increases the magnetic field around the
wire. Answer True
11
True or False The magnetic field strength of a
magnet is weakest at the poles. Answer False
12
An electromagnet is a a) temporary
magnet b) permanent magnet Answer a
13
True or false Voltage can be reduced with a
step-up transformer. Answer false
step-down transformer
14
True or False Increasing the number of loops of
wire in an electromagnet increases the strength
of its electric field. Answer True
15
True or False Magnets may be monopoles. Answer
False
16
True or false An electromagnet consists of a
current-carrying wire coil surrounding an iron
core. Answer T
17
Having two distinct and opposite
ends a) magnetic flux b) polarization Ans
wer b
18
What is a vector quantity that exists in a region
of space where a magnetic force
occurs? a) magnetic field b) magnetic
flux Answer a
19
True or false Maglev is short for magic
levitating train Answer false magnetic
levitating train
20
True or false Magnetic field lines show the
direction and shape of the magnetic field around
a magnet. Answer T
21
What does a transformer transform? a) voltage
b) charge Answer a
22
A magnet created when current flows through a
wire coil a) solenoid b) electromagnet An
swer b
23
A group of neighboring atoms that have their
magnetic fields aligned in the same
direction a) polarization b) domain Answe
r b
24
True or False Michael Faraday discovered that
changing magnetic fields create electric
current. Answer True
25
A device to measure very small currents a) galv
anometer b) electromagnet Answer a
26
True or False The earths geographical north
pole is near its magnetic south pole. Answer
True
27
True or false Magnetic forces or fields are
produced by stationary electric
charges. Answer F
28
True or False Magnetic field lines point from
south to north. Answer False
29
True or false Motors and generators both use an
electromagnet to change energy from one form to
another. Answer T
30
True or false In a step-down transformer, the
primary coil has more loops than the secondary
transformer. Answer T
31
True or false Moving magnets produce electric
forces or fields. Answer T
32
True or false Junk yard electromagnets work
because current is flowing through a wire
coil. Answer T
33
A long coil of wire consisting of many
loops a) solenoid b) galvanometer Answer
a
34
True or false In a generator, electrical energy
is used to produce mechanical energy. Answe
r F - motor
35
True or false Electricity and magnetism are two
aspects of the same force. Answer T
36
Swiping your credit card allows a magnetic strip
on the back to pass a wire coil. What principle
explains this process? a) Electric current
creates a magnetic field. b) A changing magnetic
field produces an electric current. Answer b
37
True or False Like poles attract and opposites
repel. Answer False
38
True or false Generators produce electrical
current by placing a wire coil in a changing
magnetic field. Answer T
39
The number of magnetic field lines passing
through a surface a) magnetic
flux b) domain Answer a
40
Maglev trains can achieve such high speeds
because they are a) floating on a cushion of
air b) aerodynamic c) both Answer c