A power supply and a solar cell are being compared with the potentiometer circuit illustrated. The potentiometer wire PQ is $100.0\,\text{cm}$ in length and its resistance is $5.00\,\Omega$. The power supply has an e.m.f. of $2.000\,\text{V}$, whereas the solar cell has an e.m.f. of $5.00\,\text{mV}$. What value of resistance $R$ should be chosen so that the galvanometer gives a zero reading when PS $= 40.0\,\text{cm}$?
- A$395\,\Omega$
- B$405\,\Omega$
- C$795\,\Omega$
- D$805\,\Omega$