Series and Parallel Circuits 2 Lab - University of Michigan



SERIES AND PARALLEL Circuits - IIUM Physics Demo Lab 07/2013EXPLORATIONMaterials1 green multimeter (with leads)1 battery board1 alligator lead cardBuild the circuit shown in the schematic below: Figure SEQ Figure \* ARABIC 1: A Simple Series CircuitPrediction: If you attach an alligator lead between point 1 and 2, what will happen to the first light bulb when you close the switch? How is it different from the system without the alligator lead? Will it affect the brightness of the second light bulb, and if so, How? Discuss with your group and explain your prediction. Observation: Attach an alligator lead between point 1 and 2 and close the switch. Observe what happens to the first and second light bulbs. Does this observation agree with your prediction? Explain why or why not.2. Build the circuit shown below:Figure 4: Series and Parallel Circuit2. Predict the voltage across each bulb and across all the bulbs. Once you’ve recorded your predictions, measure the voltages. Explain your observations below.Contact PointsPredictedMeasuredExplanation of PredictionV1-2V2-3V2-4V1-4Additional explanation of your observations:3. Based on your measurement of the current for a single bulb connected to the battery in Part I of the lab, predict the current at each point in the circuit. You can also measure the current for a single bulb connected across 6 V now if you prefer. Once you’ve recorded your predictions, measure the current at each test point. Explain your observations. Single Bulb Current: __________Contact PointsPredictedMeasuredExplanation of PredictionIaIbIcIdIe4. Observe the lights with the switch closed. Are all the bulbs equally bright? Explain what you observe.What happens to the current after point 2, where there are two paths it can take to complete the circuit? How does this affect the brightness of the bulbs?5. Predict what will happen when you unscrew light bulbs in the series and parallel circuit. In each case predict how the brightness of each bulb will change. Figure 5: Series and Parallel Circuita) Predict what will happen if you unscrew bulb 1. Explain your prediction.b) Predict what will happen if you unscrew bulb 2. Explain your prediction. c) Predict what will happen if you unscrew bulb 3. Explain your prediction.6. Unscrew each bulb and observe what happens. Record your observations. Do they agree with your predictions? Explain.a) Bulb 1 unscrewed.b) Bulb 2 unscrewed.c) Bulb 3 unscrewed.Summary:The current in a circuit divides when presented with multiple paths back to the negative pole of the battery. The total current must be conserved in accordance with Junction RuleThe power dissipated in a bulb, and hence the brightness of the bulb, increases with increasing current. We can use the brightness of bulbs as an indicator of the power (current) they receive and predict the relative brightness of bulbs based on the relative amounts of the current they receive.Final Clean-upPlease disconnect all alligator leads and reattach them to the clip card. Replace all equipment to the carts. ................
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