Answer
$427.7nm$
Work Step by Step
We know that
$E=\frac{hc}{\lambda}$
This can be rearranged as:
$\lambda=\frac{hc}{E}$
We plug in the known values to obtain:
$\lambda=\frac{6.626\times 10^{-34}\times 2.9979\times 10^8}{4.645\times 10^{-19}}$
$\lambda=4.277\times 10^{-7}m=427.7nm$
