Four copper wires of equal length are connected in series. Their cross-sectional areas are $1.00 \mathrm{cm}^{2}, 2.00 \mathrm{cm}^{2}$ $3.00 \mathrm{cm}^{2},$ and $5.00 \mathrm{cm}^{2} .$ A potential difference of $120 \mathrm{V}$ is applied across the combination. Determine the voltage across the $2.00-\mathrm{cm}^{2}$ wire.