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Paper 2
magnetism and electromagnetism
The motor effect
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Created by
Ellie MacKay
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Cards (18)
What is produced when current flows through a conducting wire
A
magnetic
field is produced around the
wire
What determines the strength of the magnetic field around a current - carrying wire
The
magnitude
of the
current
flowing through the wire
the
distance
from the wire
What is a solenoid
A
coil
of
wire
which when
current
passes through creates a strong
magnetic
field
Describe the magnetic field found inside a solenoid
Strong
and
uniform
What’s an electromagnetic
A
solenoid
with an added
iron
core
padding the iron core
increases
the
strength
of the magnetic field
What is the motor effect
When a
force
is exerted between a
magnetic field
and a current-carrying
conductor
placed in that field
What rule is used to determine the force experienced due to the motor effect
Flemings left hand rule
When using Flemings left hand rule what does the forefinger represent
The
forefinger
points in the direction of the
magnetic
field
When using Flemings left hand rule what does the second finger represent
The
second
finger points in the direction of
current
flow in the
conductor
What factors affect the size of the force on a current-carrying wire in a magnetic field
The
magnitude
of the current flowing through the
conductor
the
strength
of the magnetic field that the
conductor
is placed in
If the direction of current in a current-carrying wire placed in a uniform magnetic field is reversed, what happens to force
The
direction
of the force is
reversed
If strength of the current in a current-carrying wire placed in a uniform magnetic field is increased what happens to the force
The strength of the force is
increased
What criteria must be met for the equation linking force, magnetic flux density, current and length to hold
The
conductor
must be at
right
angles to the
magnetic
field it is placed in
What unit is used for magnetic flux density
Tesla
(
T
)
How does an electric motor work
A
coil
of
wire
,carrying a
current
, is placed in a
magnetic field
the forces on the two sides
perpendicular
to the
field
experience forces in
opposite
directions
this causes a
rotational
effect
How do loudspeakers make use of the motor effect
The
motor effect
is used to convert
variations
in the
current
of an
electrical circuit
into the
pressure
variations which produce
audible
sound
Explain how a loudspeaker works
A
cone
with a
wire
wrapped around it is connected to an a.c.
Power
supply and is placed in a
permanent
magnetic field
when
current
flows through the wire, it creates a
second
magnetic field which interacts with the
permanent
field
this produces a
force
which causes the cone to
vibrate
How is the pitch of the sound from a loudspeaker changed
The
frequency
of the
a.c
current is altered
this creates a different frequency of
vibration
in the
cone