Answer
$1.5×10^{4}$ V
Work Step by Step
Recall the relation λ= $\frac{1.227}{\sqrt V}nm$ where λ is the wavelength and V is the magnitude of accelerating potential.
Thus we get,
V=$(\frac{1.227}{ λ(nm)})^{2}$= $(\frac{1.227}{0.010})^{2}$= $1.5×10^{4}$ volts