Section 1

1. While we can draw circuits using pictures, it is much simpler to use circuit diagrams which represent each type of circuit element with a special symbol. Here we see a picture (above) and circuit diagram (below) of a bulb connected by two wires to a battery.

2. Here is the list of the symbols for the circuit elements we'll be using:

3. Circuit diagrams indicate electrical connections, not geometrical arrangements.

Section 2

1. Electric current is a flow of something around a closed loop or circuit. The more current that flows, the brighter the bulbs in our circuits.

2. Flow of Electrons: Electrons flowing from a low potential to a high potential is called a flow of electrons. In our circuit, the electrons exit the negative pole of the battery, flow around to the positive pole and then through the battery to the negative pole where they repeat their journey.
The electrons involved are the electrons that make up the battery and the wires. No electrons are produced by the battery.

3. (Conventional) Current: Positive charges flowing from a high potential to a low potential is called a Conventional Current or more simply a current. This is always what we mean by a current.

Section 3

1. Materials that allow a current to flow easily are called electrical conductors. Materials that don't allow (much) current to flow are called insulators.

Section 4

1. Current: The current, in amps, is the amount of charge/time passing a given point. For a simple, single loop circuit, the current is the same at all points. Current does not get "used up" in a circuit. An ammeter is a device used to measure current.

2. One ampere (amp) is the current at a point in a circuit if one Coulomb of charge flows past that point every second.
/td>	I is current in Amps Q is charge in Coulombs t is time in seconds

3. Meter Polarities: The + and - sides of any meter must be connected to the + and - sides of the battery, respectively. These connections may be indirect, that is, other elements may be present within the paths back to the battery.

Section 5

1. Electrical Potential: If a Coulomb of charge at a point has one Joule of potential energy, that charge is at a potential of one volt.
	V is voltage in Volts PE is potential energy in Joules Q is charge in Coulombs

2. The voltmeter is designed to measure the change in voltage, the potential difference or voltage drop, between a pair of different points in the circuit. You don't open up the circuit and let the current pass through it like with an ammeter. Instead you clip a wire from the + terminal of the voltmeter to one point in the circuit and a wire from the - terminal of the voltmeter to some other point closer to the - pole of the battery. The voltmeter will then tell you the voltage drop between these two points.

3. The Emf (electromotive force) of a battery (or other voltage source) is the voltage increase (energy/charge) provided to the charges as they pass through the Emf source.

4. The Voltage Drop is the loss in voltage (energy/charge) as the current passes through the circuit.

5. Kirchhoff's Loop Rule: Around a complete circuit the sum of the voltage increases equals the sum of the voltage drops. For our circuit, this means that the Emf (an increase in voltage) equals the sum of the voltage drops across the bulbs.

Section 6

1. Power is the rate at which work is done or energy is transformed or transferred.
	P is Power is in Watts W is Work (or Energy) in Joules t is time in seconds

2. Electrical Power
	P is Power is in Watts I is Current in Amps V is voltage in Volts

Section 7

1. The amount of current passing through a conductor is directly proportional to the voltage drop across it and vice versa.

2. The amount of current passing through a conductor is inversely proportional to resistance in the conductor.

3. Ohm's Law: The current through a conductor is directly proportional to the voltage drop across it and inversely proportional to its resistance.
	I is current in Amps(A) V is voltage drop in Volts (V) R is resistance in Ohms (&)

4. Power Equations: P = IV P = I2R P = V2/R

Section 8

1. Circuit elements connected end to end, with no branching between, are said to be connected in series. Below we represent three resistances in series. They might be bulbs or sections of wire, for example.

Section 9

1. Circuit elements connected with common end points are said to be connected in parallel.
Here we represent three resistances in parallel. When the current comes to such an arrangement, it divides. Some of the current goes through each branch.