many devices depend on the electric motor including: fans computers elevators car windows amusement park

rides

Michael Faraday (1821) wanted to see if a magnet could move a conductor just like a conductor could move a compass needle

his experiment was successful and he created the first electric motor

the motor worked because the magnetic field in the copper wire interacted with the magnetic field of the permanent bar magnet

one magnetic field is from a current-carrying conductor, the other is from the external magnets

when the two interacting magnetic field lines are pointed in the same direction there is a repulsion force

when the interacting field lines are pointed in opposite directions, there is an attraction force

the final result is the conductor being forced downward

describes movement of a current-carrying conductor in an external magnetic field

“a current-carrying conductor that cuts across external magnetic field lines experiences a force perpendicular to both the magnetic field and the direction of the electric current”

magnitude of the force depends on the magnitude of the external field and magnitude of the current

hold your hand flat with your thumb at a right-angle to your fingers

if the fingers point in the direction of the external magnetic field and your thumb points in the direction of the conventional current, then your palm faces the direction of the force on the conductor

note: if you follow electron flow instead of conventional current, then use the left-hand rule

one of the first practical uses of the motor principle was the development of meters measuring electrical quantities

are both made from a galvanometer and a resistor that protects the sensitive coils of the looped wire

both ammeter and voltmeters actually measure current, but the voltmeters scale is determined by the Ohm’s law relationship, yielding voltage

an external magnetic field can cause a current-carrying conductor to move

the motor principle states that the current-carrying conductor experiences a force perpendicular to both the magnetic field and the direction of the electric current

the magnitude of the force on a current-carrying conductor depends on both the magnitude of the external magnetic field and the magnitude of the current

the right-hand rule for motor principle states that if the fingers point in the direction of the magnetic field lines and your thumb points in the direction of the conventional current, then your palm faces the direction of the force on the conductor

analog meters operate according to the motor principle