Preliminary Experimental Work

1. Determine the resistance of four different resistors on your desk from their color codes (notice there are two the same of each resistance type). In your notes refer to them as resistors A, B, C, D with A being the lowest resistance and D the highest. The rest of this lab's experiments will refer to them with these letters.

2. The two types of meters on your desk will be used to measure the voltage and current within a circuit. Notice the scale used on the meters is determined by terminal you input the wire. The value on the terminal indicates the maximum on the meter scale.

• The voltmeter (V) measures the potential difference between two points of a circuit. Potential difference (voltage) is measured by connecting the voltmeter across (in parallel) components of the circuit.

• The ammeter (A) measures the current that flows through a wire. Current is measured by breaking the circuit and connecting the ammeter in line (in series) with the circuit.

Notice also the meters have a polarity (positive and negative inputs). The current flow from a battery is directional as indicated by the polarity on a battery. Often the positive side is denoted by red and negative by black.

3. Measure the potential (voltage) of one, two and three batteries connected in series.

4. The animated pictures here illustrate the differences between series an parallel circuit showing current flow as red dots.

• In the series circuit notice the current (the number of red dots) is the same in any part of the circuit.
• For the parallel circuit the current divides between the two parts.