\textbf{198.} In a photoelectric experiment, the longest wavelength that can separate an electron from a metal plate is 480 nanometers. What wavelength (in nanometers) of light with a voltage cut-off of 1.5 volts?
\[
\left(C = 3\times10^{8}\ \frac{\text{m}}{\text{s}},\ h = 4\times10^{-15}\ \text{eV.s}\right)
\]
\[
\text{(1)}\ 300 \qquad \text{(2)}\ 350 \qquad \text{(3)}\ 400 \qquad \text{(4)}\ 450
\]