A relay must be able to run $800\,\text{m}$ away from its power supply. The power supply’s internal resistance is negligible. To function, the relay needs $16.0\,\text{V}$ and a current of $0.60\,\text{A}$. A cable links the relay and the power supply, and two of the wires inside the cable are employed to deliver power to the relay. Each of these wires has a resistance of $0.0050\,\Omega\,\text{per metre}$. What is the minimum output e.m.f. from the power supply?
- A$16.6\,\text{V}$
- B$18.4\,\text{V}$
- C$20.8\,\text{V}$
- D$29.3\,\text{V}$