Circuits Lab Directions

Name:______Date:______Hour 1 2 3 4 5 6

Objective: Build a simple circuit, series circuit, and parallel circuit from the lab equipment. Be able to compare and contrast between each type. Think about electronic devices in your life, can you tell which are series, parallel, or both?

Materials: Circuit kit – 2 D batteries and cradles, 2 light bulbs, single throw switch, dimmer switch, connecting wires

Procedure: In total, there are 4 circuits to build. Be careful to construct them exactly as the picture or it won’t work properly, answer the questions about its operation, and then go on to the next circuit.

DO NOT LEAVE THE CIRCUITS ON FOR MORE THAN 10 SECONDS AT A TIME. Turn them on to make some observations but turn them off to talk and answer the lab questions. Leaving the circuits on will drain the batteries.

Circuit 1

Circuit 3 Circuit 4

Circuits Lab Write-up

Circuit 1

1. What type of circuit do you think this is?______

2. When the switch is “open” is the light on or off?______

3. So an “open” switch must mean ______and a “closed” switch must mean ______.

4. If the bulb had a resistance of 30 ohms, fill in the values for ohm’s law for this circuit. Show all necessary work, answer, and units.

V = ______I = ______R = ______

5. You can touch any of the open connections of the circuit and you don’t feel any shock, why? ______

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Circuit 2– Between the connection for the bulb and battery of circuit 1, add the dimmer dial so that the wires to from the bulb to 1 side of the dimmer dial, and then from the other side of the dimmer dial to the battery.

6. Have you changed what type of circuit this is? ______

7. With the dial turned all the way up, how does the brightness of the bulb compare to circuit 1?

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8. As you turn the dial down, what happens to the brightness? ______

9. Which of the 3 parts of a circuit do you think the dimmer dial is changing; V, I, or R? Explain.

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Circuit 3

10. What kind of circuit is this? Explain how do you know? ______

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11. How does the brightness of the bulbs compare to Circuit 1? Why do you think? ______

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12. What would happen if you unscrew 1 light bulb? Why? ______

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13. If each bulb had a resistance of 30 ohms, fill in the values for ohm’s law for this circuit (V1, V2, Vt, I1, I2, It, R1, R2, Rt). Show all necessary work, answer, and units.

Circuit 4

14. What kind of circuit is this? Explain how do you know?______

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15 How does the brightness of the bulbs compare to circuit 1? Why do you think? ______

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16. What would happen if you unscrew 1 light bulb? Why? ______

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17. If each bulb had a resistance of 30 ohms, fill in the values for ohm’s law for this circuit (V1, V2, Vt, I1, I2, It, R1, R2, Rt). Show all necessary work, answer, and units.

18. Which circuit would drain the batteries quickest? Why? ______

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Circuit 5 - Recreate circuit 1, and then connect a dimmer dial parallel to just the light bulb.

19. What happens to the light bulb as you turn the dimmer dial one way or the other?______

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20. What do you think the dimmer dial is adjusting and how do you know?______

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