Motor Effect Flashcards
when a current flows through a wire a what is produced around the wire
magnetic field
what is an electromagnet
a magnet that can be turned off and on (magnetically soft)
what is the electromagnet in a circuit
a solenoid with a soft iron core
what is a soft magnet
can be magnetised and demagnetised easily
what is a hard magnet
hard to magnetise but once done it stays magnetised
where is a magnetic field produced on a wire
around a current carrying conductor
how can you make the magnetic field in a circuit stronger
add more loops to the coil of the solenoid or increase the current by adding more voltage
what is the motor effect
converting electrical energy into kinetic energy
8 steps for how motor effect is used in a bell (picture found in folder)
1) switch closed –> circuit complete
2) magnet is magnetised by the electrical flow
3) armature is attracted towards the magnet enough for the hammer to hit the bell
4) the springy bit of metal is brought with it to the magnet
5) when springy strip of metal moves away from the contact point, circuit is broken
6) the electromagnet then becomes de-magnetised
7) attraction of armature stops and springs back to contact screw
8) this closes the circuit again, magnetising the magnet and repeating the process, the bell rings again quickly
8 steps for how a battery works in a car
1) switch closed –> circuit complete and current flowing
2) magnet magnetised by electrical flow
3) iron rockers are attracted to north pole of the magnet
4) pivot makes other wend of the arm create contact with the second circuit (2 circuits for safety)
5) circuit complete –> current flows
6) motor starts
7) switch in first circuit opens
8) spring retracts the contacts holding them apart
what to do to find the direction of the magnetic field
right hand thumb rule
find out directions of magnetic field flows on different object
in textbook or folder
what to do in order to predict the direction a current carrying conductor or wire will move in an external magnetic field
fleming's left hand rule thumb is force forefinger is magnetic field (always from north to south) current is middle finger do some practice for this
look at dc motor parts in
folderrrrr I’m bare tired jheezzz
current
flows of electrons
split ring communicator
changes the direction of the current
brush contacts
made of graphite/carbon
battery
converts chemical energy to electrical energy
coil
rotates in the permanent magnetic field
kinetic energy
moving objects have this
permanent magnet
has a north and south pole
force on the coil
acts at right angles to the permanent magnetic field
magnetic field
flows from north to south
dc motor
converts electrical energy into useful kinetic energy
8 steps on how a loudspeaker works (diagram in folder)
1) current from the amplifier is an ac, it flows in one direction then the other
2) theres an alternating magnetic field around the coil, its attached to the paper cone
3) coil inside a circular magnet
4) the coils magnetic field and the permanent magnetic field interact producing a force between them
5) as the coil has an ac flowing through it, magnetic field is alternating so the force acting on it also alternates
6) the field, current and forces are all at right angles to each other
7) coil vibrates due to the af, which causes the paper cone to vibrate
8) cones vibration causes variations in air pressure and sets up a longitudinal sound wave
