A cable of total length $L$, made up of two wires, connects a $12.0\,\text{V}$ power supply with negligible internal resistance to a lamp, as illustrated. The potential difference across the lamp is $10.5\,\text{V}$. The current in the wire is $2.50\,\text{A}$. Each wire is constructed from metal of resistivity $1.70 \times 10^{-8}\,\Omega\,\text{m}$ and has a cross-sectional area of $6.00 \times 10^{-7}\,\text{m}^2$. What is the value of the length $L$ of the cable?
- A$10.6\,\text{m}$
- B$21.2\,\text{m}$
- C$29.4\,\text{m}$
- D$58.8\,\text{m}$