Many of our electric circuits experiments, such as the Ohm’s Law experiment in Physics with Vernier (PWV) require students to construct circuits from batteries, resistors, light bulbs, and other electronic components. We recommend using our Vernier Circuit Board 2 (VCB2) for those labs. All of the required components are on the board already and the experiment instructions include circuit diagrams based on the board.
Those experiments can also be done using the off-the-shelf electronic components you may already have in your classroom or could easily source from electronics suppliers. Here are a few suppliers likely to have the required components:
* SparkFun (www.sparkfun.com)
* Mouser Electronics (www.mouser.com)
* Electronix Express (www.elexp.com)
* Jameco Electronics (www.jameco.com)
* Parts Express (www.parts-express.com)
* All Electronics Corp. (www.allcorp.com)
* Edmund Scientific (www.edsci.com)
* Digi-Key (www.digikey.com)
Some additional notes:
* It is important to use resistors with sufficient power ratings. The Vernier circuit experiments were designed using VCB2 resistors rated at 1 W, assuming that a 5 V power supply is used. If you use a lower voltage power supply, you can use resistors rated at lower power. Power ratings that are too high are never a problem. Small resistors (10 Ω or less especially) should be rated to at least 1 W.
* Resistors are labeled with a resistance and a tolerance in %, which specifies how much the value may vary from the rated value. The VCB2 resistors have a 5% tolerance. Capacitors often have 10% or 20% tolerances. Do not expect outstanding agreement with the marked values. You may want to have students measure the resistance with a good ohmmeter and the capacitance with a trusted capacitance meter, if available.
* When purchasing light bulbs, pay close attention to their voltage rating; you want to buy a bulb that matches your power supply. Connecting a 2 V light bulb to a 5 V power supply will quickly burn out the bulb.
* Non-polarized capacitors are convenient to use since they can be placed in the circuit either way. If you choose to use an ordinary polarized electrolytic capacitor, the negative side of the capacitor must be connected to the negative battery terminal or the circuit will not work. In fact, if wired backward, electrolytic capacitors can be destroyed.