🔋 Current electricity — emf pushes, resistance opposes, I = V/R settles it

A cell of emf ε drives charge round a closed loop. Across the resistor the potential drops by V = IR, and that lost electrical energy reappears as heat at the rate P = I²R. Change R or ε and watch the current, the voltage and the heating all respond together.

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The cell's emf ε pushes positive charge from − up to + inside it (brown arrow), so a steady current I runs round the outside loop.

emf ε 6.0 V

Resistance R 6.0 Ω

Ohm's law I = V/R = — A · V = I·R = — V
heating P = I²R = — W · with internal r = 0.50 Ω, I = ε/(R+r)

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