The meter was defined in 1963 as 1,650,763.73 wavelengths of radiation emitted by krypton-86 (it has since been redefined). What is the wavelength of this krypton-86 radiation? To what region of the electromagnetic spectrum does this wavelength correspond (i.e. infrared, ultraviolet, x-ray, etc.)? What energy does one photon of this radiation have?
I don't really understand what the question means when it says this, what does the meter have to do with the wavelength emitted by krypton-86? I may just be reading the question wrong, if anyone could clear this up it would be greatly appreciated!