SP8c Magnetic Forces Flashcards
Why can any wire carrying a current experience a force in a magnetic field?
because the current in the wire creates a magnetic field, and this interacts with the field.
What kind of force do magnets experience in a field?
an equal and opposite force.
When does the greatest force on a wire occur?
when it is at right angles to a field.
When is there no force experienced on a wire?
when it is in the same direction as a field.
What does Fleming’s left-hand rule show?
the direction of the force on a wire, the magnetic field, and current.
What do fingers represent in Fleming’s left-hand rule?
.thumb - force
.index finger - magnetic field
.middle finger - current
What is the strength of a magnetic field called?
the magnetic flux density.
Whta is magnetic flux density measured in?
newtons per ampere metre or tesla
force = ?
magnetic flux density x current x length
What is the function of carbon brushes in a electric motor?
they make electrical contacts between the circuit and the motor.
What is the function of a split-ring commutator in a electric motor?
changes currents direction every half turn.
