Voltage – Electrical Potential Voltage – or electric potential, is the energy each electron has as it moves through a circuit. The symbol for electric potential is V and the units are volts (V).

In order to measure the electric potential we need to determine how much energy (Joules) each coulomb has (6.0 x electrons). V = Eelectric potential = energy (joules J) Q charge (coulombs C)

Example A If a battery uses 45J of energy with a charge of 15C what is the electric potential of the battery? V = E / Q = 45J / 15C = 3 V

Example B How many joules of energy are released from a 9V battery that has a charge of 25C? E = V x Q = 9 V x 25C = 225 Joules

Practice Problems: 1.What is the potential difference in a battery if the charge is 45 C and 155 J of energy are used? V = E / Q = 150 J / 245 C = 3.4 V

2. If a 9 V battery has a charge of 46 C how much chemical energy does the battery have? E = V x Q = 9 V x 46C = 414 Joules

3. What is the charge of a battery if it is 9 V and has 600 J or energy? Q = E / V = 600 J / 9 V = 66.6 C

4. How many joules of energy are released from a 6V battery that has a charge of 250 C? E = V x Q = 6 V x 250 C = 1500 Joules

5. If a battery uses 85 J of energy with a charge of 25C what is the electric potential of the battery? V = E / Q = 85 J / 25 C = 3.4 V

SymbolUnitsUnit Symbol Formula Current I ampsA I = Q / T TimeTsecondsS t = Q / I ChargeQcoulombc Q = I x t OR Q = E / V Electric Potential VvoltsVV = E / Q EnergyEjoulesJE = V x Q OR E = P x t PowerPwattsWP = E / t