1. Storing Electrical Energy 4.1.5 Electrical Potential (Voltage)

2. Electrical PE
To increase PE - + + +
To decrease PE - + + +

3. Calculating Potential Difference
Amount of potential difference:
WORK DONE PER UNIT CHARGE
1 VOLT = 1 J/C

4. Example #1
6.0 joules of work are done in pushing an object with +3.0 coulombs of charge toward a charged plate.
What type of charge does the plate have on it?
How much potential energy was stored in the electric fields?
How much electrical potential was generated?
V = W/q
V = 6.0 J / 3.0 C
V = 2.0 V
Positive
6.0 J

5. Example #2
An object with a 2.0 coulomb charge is accelerated through a potential difference of 10 volts.
How much kinetic energy does the object gain?
V = W/q
W = Vq
W = (10 V)(2.0 C) = 20 J

6. Electron-volts Alternate unit for work/energy:
Raises 1e to an electrical potential of 1 V
1 eV = 1.6 x J
What is the energy needed to raise four electrons to a potential of 2.5 volts?
What is the energy needed to raise two electrons to a potential of 1.0 volt?
V = W /q
2.5 V = W / 4e
W = 10 eV
V = W /q
1.0 V = W / 2e
W = 2.0eV

7. Example #3
An electron travels a distance of 2.0 x 10-3 meter as its electrical potential is raised by 300 volts.
How much work is done on the electron?
V = W/q
300 V = W / 1e
W = 300 eV
V = W/q
300 V = W / 1.6 x C
W = 4.8 x J

8. End of PRACTICE