1. Gravitational Potential vs. Gravitational Potential Energy

2. Voltage is not the same as electrical potential energy, because voltage is potential energy per unit of charge.

3. Circuits require high potential and low potential—a potential difference or Voltage.

4. Batteries require a voltage…they do the work that keeps a circuit “flowing”.

6. Did you find these configurations?

8. Why are these successful?

10. For a circuit to “work”:
There must be an energy supply capable of 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 that stretches from the high potential, positive terminal to the low potential, negative terminal.

11. What is current?

12. Do you notice a problem?

13. Conventional Current:
Ben Franklin, who conducted extensive scientific studies in both static and current electricity, envisioned positive charges as the carriers of charge. As such, an early convention for the direction of an electric current was established to be in the direction that positive charges would move. The convention has stuck and is still used today. The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery. Electrons would actually move through the wires in the opposite direction. Knowing that the actual charge carriers in wires are negatively charged electrons may make this convention seem a bit odd and outdated. Nonetheless, it is the convention that is used worldwide. So you have to just get used to it!

15. When an electrochemical cell no longer works, it is out of charge and must be recharged before it can be used again.
T or F
b. An electrochemical cell can be a source of charge in a circuit. The charge that flows through the circuit originates in the cell.
c. Charge becomes used up as it flows through a circuit. The amount of charge that exits a light bulb is less than the amount that enters the light bulb.
d. Charge flows through circuits at very high speeds. This explains why the light bulb turns on immediately after the wall switch is flipped.
e. The local electrical utility company supplies millions and millions of electrons to our homes everyday.

16. What is resistance?

17. Quantity
Symbol
Equation(s)
Standard Metric Unit
Other Units
Potential Difference (a.k.a. voltage) V
V = PE / Q
V = I • R
Volt (V)
J / C
Current I
I = Q / t
I = V / R
Amperes (A)
Amp or C / s or V / Ω
Power P
P = Work or PE / t
Watt (W)
J / s
Resistance R
R = V / I
Ohm (Ω)
V / A
Energy
E or PE
PE = V • Q PE = P • t
Joule (J)
V • C or W • s