Terminal Voltage & Internal Resistance (V = E − Ir (discharging cell, current out of + terminal))

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V = E − Ir (discharging cell, current out of + terminal)

What each symbol means

SymbolWhat it stands for
EEMF (V)
ICurrent through cell (A)
VTerminal voltage (V)
rInternal resistance (Ω)

When to use this

Single source approx; steady DC; I positive when cell supplies energy to external circuit.