Coding classes in Gwynedd

The numbers in the model are invented. A station must deliver 500 kilowatts to a quarry through a line whose wires, there and back, have a resistance of 4 ohms. Power equals voltage times current, so the higher the voltage, the smaller the current needed. The heat lost in the wires equals the current squared times the resistance. The learner codes the simple version first: current is power divided by voltage, loss is current squared times resistance, and prints a table.

At high voltage the simple formula is close enough. At low voltage it produces nonsense: a loss bigger than the power being sent. That is the signal that the model has broken. The simple version assumes the full sending voltage reaches the load, but a big current makes the voltage fall along the wires. The proper version accounts for that drop, which turns the problem into a quadratic equation for the current. When the quadratic has no real solution, the answer is that no current can deliver the power at all. At 2,000 volts the most that can reach the quarry through our line is 250 kilowatts, however hard the generator pushes.

The pattern that made 10,000 volts attractive is clear in the numbers: ten times the voltage means a tenth of the current, and a hundredth of the heat lost. Alternating current mattered too, because transformers can step its voltage up for the journey and down again for use, but modelling transformers is a lesson for another day. The learner finishes by plotting loss against voltage and marking the point where the simple and proper answers start to agree.

Spotting an impossible answer before anyone relies on it is a reason Gwynedd teenagers should still learn to code in 2026. The longer argument is in why teenagers should still learn to code in 2026.