P: 210 $$E=hv$$ $$v=\frac{c}{\lambda}$$ so...$$\lambda=\frac{hc}{E}$$ E = energy (IN JOULES, not kJ!!) h = 6.626 * 10^-34 J*s v = frequency (s^-1) c = 3.00 * 10^8 m/s (speed of light) $$\lambda$$ = wavelength