Electric Current

Electric Potential Electrons in a circuit have potential energy –The energy is related to the force exerted by an electric field –The potential energy per unit of electric charge is called the electric potential This is measured in Joules per Coulomb

Voltage Just like water flowing downhill, electrons want to move from areas of higher potential energy to lower potential energy –The difference between the two potentials is called the potential difference –This is measured in Volts (V) –Potential difference is thus also called Voltage –Voltage, or a potential difference, between two places causes electrons to flow through a circuit

Current When there is a potential difference (voltage) between two places and a path for the electrons to travel (conductor) electrons will flow A moving charge creates an electric current. –The unit of current ( I ) is the ampere, a fundamental SI unit

Conductors In a conductor, the ‘free’ electrons are able to move When an electric field is applied to the conductor the electrons are forced to accelerate opposite the electric field. –The electrons all move in the same direction, creating a current

Current Convention Because of Ben Franklin the convention of current direction is actually opposite the direction of the electrons movement.

Amount of Current If we increase the potential difference between two positions, the current will increase Current also depends upon something called resistance –Resistance is how easy or hard it is for the electrons to move through the material –The greater the resistance in the circuit, the less current there is for a given voltage

Resistance The resistance in a wire is dependant upon –The material of the wire –The length of the wire –The width of the wire

Ohm’s Law The voltage (potential difference) in a circuit divided by the current flowing through it tells you the resistance in the circuit The unit of electric resistance is the volt per ampere or the ohm ( )