Voltage, Current, & ResistancePotential Difference [V] (Volt, v)

charge will only flow when there is a difference in

potential (voltage) across a conductor

ex. Van de Graaff generator sparks but evens out

Voltage causes electrons to flow.

Current [I] (Amperes, Amps, A)

the flow of e’s I = Q / t

1 Amp = 1 C / 1 s

Resistance [R] (Ohms, )

resists the flow of electrons (friction)

High

PressureLow

Pressureflow

voltage

Georg Simon Ohm (German)

Ohm’s Law

voltage makes the e’s want to flow (Current),

resistance makes them not want to (Resistance)

Which of Newton’s laws does this sound like?

Current = Voltage / Resistance

ex. What is the resistance of an electric frying pan that

draws 12 amps of current when connected to a 120 v

circuit?

I = 12 amps V = I R

V = 120 v 120 = 12 R

R = ? R = 10

Electric PowerElectric Power

The rate at which electric energy is converted into any

other energy

P = I V

Electric Power = Current x Voltage

1 watt = 1 amp x 1 volt = C/s x J/C = J/s

Usually measured in kilowatts.

(But must be in watts in the equations.)

If you know the power, how would you find the amount of energy?

P = E/t E = Pt

kilowatt-hours is another unit of energy:

measures the # of kilowatts consumed in 1 hour.

This is what the electric company measures off your meter!