EMF Calculator

Calculate electromotive force (EMF) for batteries and power sources

Method 1: From Work and Charge

Work Done (J):

Charge (C):

Method 2: From Circuit Parameters

Current (A):

External Resistance (ohms):

Internal Resistance (ohms):

Method 3: From Terminal Voltage

Terminal Voltage (V):

EMF Formulas

EMF = W / Q (work per unit charge)

EMF = I * (R + r) (current times total resistance)

EMF = V + I * r (terminal voltage plus internal drop)

Terminal Voltage: V = EMF - I * r