Flashcards in Topic 5.1: Electric Potential Difference, Current and Resistance Deck (14):
Define electric potential
o Electric Potential: the potential energy that each coulomb of positive charge would have if placed at that point in the field
Define electric potential difference
Electric Potential Difference (V): The work done per unit charge moving a positive test charge between two points in a circuit. V=W/Q measured in volts.
Define potential difference
the potential difference or p.d. is the energy transferred when one coulomb of charge passes from one point to the other point
Where does a potential difference act?
o A potential difference acts across a component
o Volt (1V): Unit of potential difference. One joule of electric potential energy is transferred to other forms when one coulomb flows between two points.
• 5.1.2: Determine the change in potential energy when a charge moves between two points at different potentials
o Energy transferred is equal to the amount of electric potential energy gained or to the amount of kinetic energy gained
o Electronvolt: Unit of energy. The energy required to move one electron through a PD of one volt. W (eV) = q (electron charges) x V (volts)
o 1 eV = 1.6 x 10-19 J
Define electric current
o Electric Current (I): The rate of flow of charge. Unit is the ampere. Conventional current flows from positive to negative
electrons flow from negative to positive
measured using an ammeter
• the ammeter is placed in the circuit so that the electrons pass through it
o therefore placed in a series circuit
o The current is defined in terms of the force per unit length between parallel current-carrying conductors
o Resistance (R): The ratio of potential difference across a conductor to current through the conductor.
Define the ohm
o The Ohm (1Ω): 1Ω = 1V/A
State Ohm's Law
o Ohm’s Law: The current through a conductor is directly proportional to the voltage across its ends if the temperature and other conditions are constant.
Define non-ohmic conductor
o Non-Ohmic Conductor: A conductor which does not obey Ohm’s Law so V is not proportional to I.