Current Electricity

Current

• A measure of the flow of charge.

• Ampere: Electrical measurement of the flow of electrons.

• 1 Ampere = 1 Coulomb/second.

• 1 Coulomb = 6,250,000,000,000,000,000 Electrons

Current

• Water Analogy: current is gallons per minute.

• Symbol for Current = I

Conventional Current

• Conventional current = positive charge flow.

• Electron Flow is in opposite direction

Current

Current

Voltage

• The force that pushes electrons through a wire.

• Electrical Pressure or “Potential Difference”.

• Measured in Volts• 1 volt = 1

joule/Coulomb

Voltage

• Water analogy: Voltage is the water pressure supplied by the pump (battery) or a water tower.

• The symbol for voltage = V

Resistance

• A resistor hinders the flow of current through a circuit.

• Ohm = unit of resistance (Ω)

Resistance

• Water analogy: a waterwheel, constriction in pipe, or other object that hinders flow.

• Symbol is R

Ohm’s Law

• Relates Current, Voltage, and Resistance.

• I = V/R

Or.. R = V/I

Where Does Voltage Originate?

• V = ∆PE / q

• ∆PE = work done on charge. (joules/coloumb)

Relating Voltage to Electric Field

• V = ∆PE / q– Joules/coulomb

• E = V/d– Unit is N/C

• Electric field – directly proportional to

applied voltage– Inversely proportional to

distance between plates.