Electricity
Electricity
Wire
Heat and insulation
Bulb
Calculations and electrical explanation
Live calculations
The complete path
The generator receives mechanical energy from falling water. A controlled converter supplies the circuit and stores surplus energy in the battery. If the generator stops, the battery supplies energy until empty. A full battery cannot store more: unused generator power is curtailed.
The voltage control represents an ideal regulated output from that storage system. It sets the voltage, while the connected resistance determines the current. The generator input control is its available electrical power, not an independent current through the bulb.
Current passes through the wire and the bulb’s filament, then returns to the other battery terminal. An open switch or broken filament breaks that path. Increasing voltage raises current; power in each resistance is I²R. Excess bulb power can break the filament. It stays broken until replaced.
Wires and insulation
Wire resistance is R = length ÷ (conductivity × cross-sectional area). Length includes both outward and return wire. Long, thin iron wire loses more voltage and power than short, thick copper wire. Choose “Long, thin wire”, then compare copper and iron to make the difference clear. Plastic used as the core prevents current in this ideal model.
A plastic cover around a metal core blocks electrical contact. It does not stop current inside the metal. The virtual metal bridge demonstrates this: with the cover removed it makes a short circuit across the bulb. Current rises, voltage is lost in the wire, and the 4 A fuse opens after 1.5 simulated demonstration seconds above its limit. Replace the fuse after removing the bridge.
Thermal wrap is a separate experiment: it slows heat leaving the wire. The wire can then reach a higher temperature for the same electrical power. Temperature is a simplified whole-wire thermal model, using room temperature 20°C, volumetric heat capacity 3.4 MJ/(m³·K) for all cores, and surface heat-transfer coefficient 10 W/(m²·K), reduced tenfold by the wrap. Resistance is held at its room-temperature value. Heat evolution runs 20× faster and battery time 60× faster. These are learning models, not cable-rating calculations.
Direction and AC
The moving dots represent conventional current: the direction positive charge would move. Electrons in metal drift the other way. Reversing DC changes direction while a filament bulb still heats. In AC the voltage and current reverse together, so power remains positive. Displayed AC voltage and current are RMS; heating and burnout use average power. Motion is slowed for visibility and does not show real electron speed.
Conductivity data
| Core | Conductivity at about 20°C |
|---|---|
| Copper | 59,590,000 S/m |
| Aluminium | 37,740,000 S/m |
| Iron | 10,400,000 S/m |
| Silver | 63,010,000 S/m |
| Gold | 45,170,000 S/m |
| Plastic | Ideal insulator in this model |
The bulb uses a fixed-resistance approximation; real filament resistance rises with temperature. Its glow and damage timing are illustrative. Inverter and battery losses, switching transients and charging limits are omitted. The energy ledger accounts for the loads, wire heat, battery change and curtailed generation.