This is the cost for the whole class, and $9 worth is durable goods, which can be used in the future.

In this extension to the Ohm's Law I activity, students observe just how much time it takes to use up the "juice" in a battery, and if it is better to use batteries in series or parallel. This extension is suitable as a teacher demonstration and may be started before students begin work on the Ohm's Law I activity.

Ohm's law is the basis of all electrical systems. Electrical engineers use this equation to guide the design of electrical systems. Students need a strong foundation in Ohm's law while designing circuits on their own. battery circuit components drain electricity light bulb light intensity Ohm's law parallel circuit series circuit Ohm's law series/parallel circuits (ways to connect them and have an effect on V and I) circuit components power devices that can be used to measure voltage and current 4 AAA general purpose (C-Zn) batteries 2.47 V, 300 mA light bulbs 10-12 alligator clips and wires stopwatch Recommended: 4 single battery holders 2 double battery holders 6 lamp holders Three light bulbs arranged in a parallel circuit. If the batteries used to power them are also arranged in parallel, will they last longer than batteries arranged in a series? A battery company wants to know how long their batteries will last for consumers. Voltage is very easy to measure, however finding the current is much harder. So, we will set up an experiment to time the battery life according to series and parallel circuits. The batteries in a series give off a brighter light; however they last about half the time of batteries in parallel. Batteries set up in a parallel circuit give a less intense light, but last twice the length of batteries in series. Build a circuit with 3 bulbs wired in parallel to 2 batteries wired in parallel as shown in Figure 1. Build a circuit with 3 bulbs wired in parallel to 2 batteries wired in series as shown in Figure 2. Have students guess how long each circuit will last. Measure the total current flowing through each circuit. Time how long it takes for the bulbs to stop giving off light. Time for series: ~20 minutes Time for parallel: ~ 40 minutes Questions for Students (pdf) Questions for Students (doc) Concluding Questions: As homework or a quiz, have students answer the seven questions in the attached Questions for Students handout. Conduct Ohm's Law 2, an activity in which students work to increase the intensity of a light bulb by testing batteries in series and parallel circuits.