Transcript Magnetism Review

Physics Chapters 24 & 25
True or False: Magnetic field lines form closed loops.
Answer: True
Which of these materials are used to make permanent
magnets:
a)
neodymium
b)
gadolinium
c)
ALNICO V
d)
all of the above
Answer: d
True or false: Electromagnets are useful because they can
easily be turned on and off.
Answer: T
True or False: When a magnet is allowed to swing freely, it
comes to rest aligned in the north-south direction.
Answer: True
True or false: In a motor, mechanical energy is used to
produce electric current.
Answer: F - generator
A small magnet mounted so it is free to turn
a)
b)
Answer: b
galvanometer
compass
True or False: Hans Christian Oersted discovered that
electric current creates a magnetic field.
Answer: True
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.
True or False: Increasing the current in a wire increases the
magnetic field around the wire.
Answer: True
True or False: The magnetic field strength of a magnet is
weakest at the poles.
Answer: False
An electromagnet is a
a) temporary magnet
b) permanent magnet
Answer: a
True or false: Voltage can be reduced with a step-up
transformer.
Answer: false – step-down transformer
True or False: Increasing the number of loops of wire in an
electromagnet increases the strength of its electric field.
Answer: True
True or False: Magnets may be monopoles.
Answer: False
True or false: An electromagnet consists of a currentcarrying wire coil surrounding an iron core.
Answer: T
Having two distinct and opposite ends
a)
b)
Answer: b
magnetic flux
polarization
What is a vector quantity that exists in a region of space
where a magnetic force occurs?
a)
b)
Answer: a
magnetic field
magnetic flux
True or false: Maglev is short for magic levitating train
Answer: false – magnetic levitating train
True or false: Magnetic field lines show the direction and
shape of the magnetic field around a magnet.
Answer: T
What does a transformer transform?
a)
b)
Answer: a
voltage
charge
A magnet created when current flows through a wire coil
a)
b)
Answer: b
solenoid
electromagnet
A group of neighboring atoms that have their magnetic
fields aligned in the same direction
a)
b)
Answer: b
polarization
domain
True or False: Michael Faraday discovered that changing
magnetic fields create electric current.
Answer: True
A device to measure very small currents
a)
b)
Answer: a
galvanometer
electromagnet
True or False: The earth’s geographical north pole is near
its magnetic south pole.
Answer: True
True or false: Magnetic forces or fields are produced by
stationary electric charges.
Answer: F
True or False: Magnetic field lines point from south to north.
Answer: False
True or false: Motors and generators both use an
electromagnet to change energy from one form to another.
Answer: T
True or false: In a step-down transformer, the primary coil
has more loops than the secondary transformer.
Answer: T
True or false: Moving magnets produce electric forces or
fields.
Answer: T
True or false: Junk yard electromagnets work because
current is flowing through a wire coil.
Answer: T
A long coil of wire consisting of many loops
a)
b)
Answer: a
solenoid
galvanometer
True or false: In a generator, electrical energy is used to
produce mechanical energy.
Answer: F - motor
True or false: Electricity and magnetism are two aspects of
the same force.
Answer: T
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
True or False: Like poles attract and opposites repel.
Answer: False
True or false: Generators produce electrical current by
placing a wire coil in a changing magnetic field.
Answer: T
The number of magnetic field lines passing through a
surface
a)
b)
Answer: a
magnetic flux
domain
Maglev trains can achieve such high speeds because they
are
a)
b)
c)
Answer: c
floating on a cushion of air
aerodynamic
both