2. What should be the energy of an electron so that the associated electron waves have a wavelength of 600 nm? 3. Since the visible region spans between approximately 400 nm and 700 nm why can the electron wave mentioned in Problem 2 not be seen by the human eye? What kind of device is necessary to detect electron waves? 4. What is the energy of a light quantum (photon) which has a wavelength of 600 nm? Compare the energy with the electron wave energy calculated in Problem 2 and discuss the difference. with a valncitv of 200 km/h. What is the