1. What we will do today Investigate resistors in series. Define a formula for the total resistance of resistors in series.

2. Combining resistors (Read) We are now going to investigate the effect of three resistors in series. What apparatus will be needed? What will our circuit diagram look like?

3. Resistors in Series We will measure three resistors separately and then measure them when combined: Resistance is measured using an ohmmeter. ResistorResistance (  ) R 1 (10  ) R 2 (22  ) R 3 (47  ) R T (combined)

4. Resistors in Series From our results we can see that the total resistance, R T, is the sum of all resistors in series. We can express this as a formula: R T = R 1 + R 2 + … The total resistance is ALWAYS bigger than the biggest resistor.

5. Example 1 R T = ? R 1 = 100 Ω R 2 = 200 Ω R 3 = 150 Ω

6. Example 2 R T = 15 Ω R 1 = 6 Ω R 2 = ? R 3 = 4 Ω

7. What have we learned today? For a series circuit: R T = R 1 + R 2 + …