6 Lab 1: DC Circuits
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Acknowledgment
This project is made possible with funding by the Government of Ontario and through eCampusOntario’s support of the Virtual Learning Strategy. To learn more about the Virtual Learning Strategy visit: https://vls.ecampusontario.ca.
PHY137 Stay-At-home Experiment 1
DC Circuits
What you will do
Build simple circuits using batteries, light bulbs, and wires. Explore the relative resistance of the light bulbs, and then compare it to the resistance of the wires.
What you will need
- 2 AA batteries with battery pack
- Alligator wires
- Incandescent light bulbs with sockets
- An unchanging reference of brightness: a piece of white paper with unchanging illumination (for example, illuminated uniformly by a desk lamp), or an indicator light that has an unchanging brightness (such as the power indicator of a power strip)
- Tape
Demonstration Video: https://youtu.be/Enw6-jIGATk
Procedures:
Part I – Light Bulbs in Series and in Parallel
- Install the incandescent light bulbs firmly into the light bulb sockets. Be careful not to tighten the light bulb too much (you might break it).
- [VERY IMPORTANT] When you connect alligator wires to the light bulb sockets, you need to make sure that the clamp does NOT get into contact with the barrel of the socket. Examine the structure of the socket, and briefly explain why you should avoid the contact.
- Draw the circuit diagram of two light bulbs in series powered by a battery.
- Put two batteries into the battery pack. Use the alligator wires to form a circuit in which the batteries power two light bulbs in series.
- Place the circuit beside the unchanging reference of brightness, take a photo of all lights including the circuit. Try to let the camera optimize exposure using the unchanging reference (on most phone camera apps, you can do this by tapping on the reference.)
- Draw the circuit diagram of two light bulbs in parallel powered by a battery.
- Use the alligator wires to form a circuit in which the batteries power two light bulbs in parallel.
- Place the circuit beside the unchanging reference of brightness, take a photo of all lights including the circuit, while letting the camera optimize exposure using the unchanging reference.
- Attach the photos in your lab report, and explain why the pair of light bulbs are brighter in one of the photos (Step 3 vs. Step 6).
- For each photo, briefly explain how you can tell the difference in resistance between the two light bulbs. If you do see a difference, identify the light bulb with the higher resistance. (Note that Incandescent light bulbs have different resistance at different brightness levels. Your answers for the two photos might not be consistent with each other.)
Part II – Compare the resistance of alligator wires and those of the light bulbs
- Use 2 batteries to power 2 incandescent light bulbs in series using three alligator wires. Take a photo of the light bulbs beside the unchanging reference of brightness. Put thi