Be sure to use a low-powered light bulb (e. g. , in the range of 1-10 volts).
Red and black wires are the most common, but you can use other colors too, like red and white. Don’t cut through the actual wire. You just need to cut through the plastic insulation that is covering the wire. Once you have cut it, you can peel or slide it off of the wire. Take care not to cut too deep as you are cutting through the plastic insulation over the wire. If you cut into the copper wire itself, you could weaken it and cause it to break.
If you weren’t able to get any red wires, then choose 1 of your 2 colors to be the positive wire.
Make sure to choose a light bulb with a voltage that’s within the voltage range of the power pack. If the power pack has an adjustable voltage range, set it to the lowest possible voltage when you turn on the power so that you don’t burn the bulb.
If the light does not light up, check that the leads are well connected and the power pack is plugged in and turned on.
Don’t turn on the voltage any higher than what the bulb is rated for.
It is dangerous to cut into a live wire (one with power on it). Always disconnect the circuit before cutting leads.
Leave the other terminal alone for right now.
Unlike in the previous experiment, this will not complete the circuit and turn the bulb on. In order for that to happen, you have to flip the switch! When you attach the switch to the circuit, make sure the switch is off (open). If you leave the switch on (closed), there will be voltage present when you attach the wire from the switch to the bulb holder terminal. You can also open the circuit by removing the light bulb from the holder.
