Question

determine the potential difference across the 300-ohm resistor

Explanation:

Calculate total resistance

$$ R_{\text{total}} = 150\,\Omega + 450\,\Omega + 300\,\Omega = 900\,\Omega $$

Calculate circuit current

$$ I = \frac{V}{R_{\text{total}}} = \frac{1.5\,\text{V}}{900\,\Omega} = \frac{1}{600}\,\text{A} $$

Calculate potential difference across the 300-ohm resistor

$$ V_{300} = I \times 300\,\Omega = \frac{1}{600}\,\text{A} \times 300\,\Omega = 0.5\,\text{V} $$

Answer:

\(0.5\text{ V}\)