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Lekce 4 · třída 14+
Electrics for engineers: Ohm and power
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Three pillars: U=IR (voltage = current × resistance), P=UI (power = voltage × current). 230 V × 10 A = 2300 W — more than a kettle. Series: same current, voltage splits. Parallel: same voltage, current splits. Copper conducts, cross-section decides: 1.5 mm² = 16 A max, 2.5 mm² = 25 A. Our /elektro/labor lab shows this visually. AC/DC: home 230 V 50 Hz AC, car 12 V DC.
- ●Wire heats = I²R: double current = four times the heat
- ●Protection at the weakest link: 1.5 mm² cable → max 16 A fuse
- ●DC more dangerous on disconnect: arc lasts longer — don’t pull plugs under load
⚡ 230 V at home is safety-wise not “low voltage”: already life-threatening. VDE norms require breakers and RCD/FI — check your flat.