 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