“A network of resistors behaves as a single resistor: the current through the network is proportional to the potential difference applied. Calculating the equivalent resistance of a network starts for many at high school but may come back later with more complex cases also at university. For success in science and engineering it is crucial to be skilled in these calculations but also to develop an intuition on how to make quick approximate solutions. Being an expert in handling electrical resistance networks will come into great use for other types of networks that have similar behaviour: magnetic circuits, fluid dynamics, heat conduction, traffic flow, just to name a few.
To hear is to forget, to see is to remember, and to do is to understand, so let’s practice resistor networks hands-on!
This tutorial is great for the class-room, since it can be performed by students individually or in small groups: the equipment is cheap and common (a multimeter and some crocodile clips) and the consumables are very cheap (7 resistors per experiment - they cost less than a cent each when bought in 100-packs) - The students can keep the final resistor network as a souvenir.
There are two levels: for high-school students do all the series and parallel exercises, and skip the final assignment that requires Kirchhoff law’s. For bachelor students, the series and parallel networks provide a nice warm-up to the real work, which is to solve a multi-loop network with Kirchhoff’s laws.
Supplies:
A multimeter - sold at hardware stores for as little as 5EUR
It’s helpful to have crocodile clips at the end of the measuring leads - I did this by replacing the multimeter cables with banana cables and attaching crocodile clips. An alternative is to attach crocodile leads to the end of the multimeter leads.
2 more Crocodile leads - sold online for as little as 1 or 2 EUR for a pack of 10
7 identical resistors. 100Ohms or 1kOhm are fine. Common 0.25W 1% types will do. We’ll call the resistance value ‘R’ from now on, to get into the right habit of doing math with symbols.”