Video: Watch this demo | Demo #2: with Resistor
Description: This demo shows two sets of lightbulbs in series and parallel configuration. Can also be used to show what happens when you remove a light bulb, or use different wattage bulbs.
Equipment:
- VariAC
- Set of light bulbs connected in series
- Set of light bulbs connected in parallel
- VariAC to banana plug cable with an alligator clip (or two)
Setup Procedure:
- Check to make sure all light bulbs have the same power rating and are screwed in tight.
- Check to make sure the VariAC works and all lights work.
- If the professor requests, include light bulbs of different wattage’s.
- When the professor is done, make sure all bulbs are the same power rating before putting away.
Demonstration Procedure:
Series Lights
- Connect the cable to include all the lights in series.
- Turn on the VariAC and set it to a high voltage. Note that the lights don’t get very bright.
- (Optional) With the VariAC off, you may also connect the cable to fewer lights to show that the remaining become brighter.
- Unscrew one light and show that all the lights go out.
- (Optional) You may swap out a few bulbs with ones of different wattages and note the effect it has.
Parallel Lights
- Connect the cable to include all the lights in parallel.
- Turn the VariAC to a lower voltage and turn it on. Note that even at a lower voltage the bulbs are brighter.
- Unscrew one bulb and note that the rest of the lights stay on.
- (Optional) You may swap out a few bulbs with ones of different wattages and note the effect it has.
- When finished, turn off the VariAC.
Concept: The idea here is to show the difference in functionality between series and parallel circuits. Objects that are connected in series depend on one another, while objects in parallel function independently. For example, if a bulb in a series of light bulbs burns out, the rest will burn out as well. However, if a bulb in a parallel circuit burns out, it will not effect the rest of the bulbs.
28-F4
