1. Voltage
And you

2. A small positive test charge (qo) would move from point A to B
* F = E qo
(parallel to F = ma)
qo pt. A
qo has more EPE than qof
Volt = electric potential = J/C qof pt.B
(potential difference, electromotor force, EMF)

3. SO VOLTAGE IS:
A measure of the difference in electric potential at 2 separate points (or terminals on a battery)
This electric potential is transformed into other forms of energy (kinetic, heat, light)
If charges flow then potential can equalize

4. Battery example:
++ charges not equalized = ++ Potential difference present ++ therefore voltage present + + charges equalized = + + no potential difference + + = no voltage

5. What can be done with voltage
All electronic devices transform EPE into other forms of energy – through the movement of charges (light, heat, magnetic fields)

6. EX: Transatlantic cable – Morris code communications
When the war of 1812 treaty was signed in Europe, the fighting did not stop across the Atlantic for weeks – because there was no way to communicate
~ 1850 work began on first transatlantic cable
Very heavy and thick – problems with breaking, sinking to bottom of ocean

7. Voltage and EPE are measureable only in terms of work – one point relative to another point (just like GPE at one height is relative to GPE at an arbitrary zero point)

8. Back to the Voltage Basics
A + chg. accelerates from region of high electric potential (voltage) to regions of low electric potential.
A – chg. Accelerates from regions of low to high electric potential

9. Voltage equation summary:
V = Joules/Coulomb = RI (resistance x current)
= Ohm’s law
Show PHET battery simulation
R = resistance to the flow of charges
Units of resistance: Ohm

10. Electrodynamics investigation introduction
Flow of charges = current (I)
= charge/time
= Δq/Δt
1 coulomb/ 1 sec = Ampere (amps)
DC = direct current (moves in same direction)
AC = alternating current (changes directions)

11. POST LAB
Battery voltage has no voltage oscillations = DC = direct current
In series has additive effect on voltage