[填空题]
John is sitting on a hdx by0-w(8y)j, hn 6 9tjjophbeach on w/ekcf*r65wveq *zk 2a warm summer evening watching the reddish sky ($\lambda$=650nm) while his brother, Eric, is playing with his laser beam with a frequency of $4.60\times10^{14}s^{-1}$.
1.Calculate the frequency of the radiation from the red sky. $\times10^{14}s^{-1}$.
2.Calculate the wavelength of the laser beam of Eric. nm
3.Compare the wavelength of the laser beam with the wavelength of the radiation of the red sky.
4.Deduce the colour of the laser beam of Eric.
