1. Bellwork
In a closed circuit, if .17 amperes of current go into a light bulb then what is the current going out of the light bulb?

2. Bellwork
Three metal spheres have charges of 3 coulombs, 7 coulombs, and 5 coulombs respectively. Say we bring all three together so that they touch and then we separate them back to their original positions. What will be the charge on each of the metal spheres after they have been touched and moved back to this original position?

3. Voltage
Physics
March 2010
Mr. Turkett

4. Electric Field and Voltage
Internal Circuit
External Circuit
Movement of charge requires energy +
High Potential - +
Low potential
High potential
Low potential
High potential E V
Light
Heat
Low Potential -

5. Water Pump Analogy Revisited
Downhill
LOW
HIGH - +
Low potential
High potential
Low potential
High potential
Light
Heat
Uphill

6. Requirements
There are two requirements which must be met in order to establish an electric circuit. The requirements are
There must be an energy supply capable doing work on charge to move it from a low energy location to a high energy location and thus establish an electric potential difference across the two ends of the external circuit.
There must be a closed conducting loop in the external circuit which stretches from the high potential, positive terminal to the low potential, negative terminal.

7. Potential Difference V = voltage (volt - V) W = work (J)
q = charge (C)

8. Electronvolt
The amount of work done on an elementary charge that is moved against an electric field through a potential difference of one volt.
W = Vq = (1.00 volt)(1.6 x C) = 1.6 x J
This amount of work, or gain in potential energy, is called an electronvolt, eV.
1.00 eV = 1.6 x J

9. Example 1
If 4.6 x joules of work is required to move an electron around an electric circuit, what is the potential difference inside the circuit?

10. Example 2
How much energy is needed to move one electron through a potential difference of 1.0 x 102 volts?

11. Example 3
Moving a point charge of 3.2 x coulomb between points A and B in an electric field requires 4.8 x joule of energy. Calculate the potential difference between these points.

12. Potential Difference
Assume d = r:

13. Linking Concepts F = E*q E = F/q F = U/r E = V/r U = F*r V = E*r
V = U/q
U = V*q