Determine the EMF of the circuit, if the current is 2.5 A, the internal resistance is 0.1 Ohm, the external resistance is 12.4 Ohm.

Let us recall the formula given to us in the physics textbook of the 10th grade of the basic course for a complete circuit:
I = E (epsilon) / R + r
E = I * (R + r) = 2.5 * 12.5 = 31.25V

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