A battery with electromotive force (e.m.f.) $9.0\,\text{V}$ and internal resistance $1.0\,\Omega$ is joined to a fixed resistor of resistance $5.0\,\Omega$ and a potentiometer whose maximum resistance is $3.0\,\Omega$, as illustrated. The sliding contact on the potentiometer is then moved through its entire range of motion. What is the largest value of the potential difference measured by the voltmeter?
- A$3.0\,\text{V}$
- B$3.4\,\text{V}$
- C$4.5\,\text{V}$
- D$5.4\,\text{V}$