Question

10 volt cell was used to drive a circuit with an external resistor of resistance of 4 ohm and internal resistance of 1 ohm. Determine the current delivered by the cell

Answer 1

On the figure below $r_i = 1\Omega$, $R_e = 4 \Omega$.

As far as the resistors are connected in series, the total resistance is:

$$R = r_i + R_e = 1+4=5\Omega$$

According to the Ohm's law, the current delivered by the cell is:

$$I = \dfrac{V}{R} = \dfrac{10V}{5\Omega} = 2A$$

Answer. I = 2A.