The Work Function ($\varphi$) corresponds to the minimum energy required to eject an electron. This energy corresponds to a maximum wavelength (threshold wavelength ${\lambda }_0$): $E=\frac{hc}{{\lambda }_0}$ Using the shortcut $E(\text{eV})=\frac{1240}{\lambda (\text{nm})}$: $3.3=\frac{1240}{{\lambda }_0}⟹{\lambda }_0=\frac{1240}{3.3}\approx 375.76\text{ nm}$ Rounding to nearest significant figure: $376\text{ nm}$.

• Light with wavelength shorter than $376\text{ nm}$ (more energy) will cause emission.
• Light with wavelength longer than $376\text{ nm}$ will not.