A line in the spectrum of atomic mercury has a wavelength of 256 nm. When mercury emits a photon of light at this wavelength, the frequency of this light is

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There are two-speed cameras, one in an are where the speed limit is 30 km/h and another where the speed limit is 50 km/h. in which will there be a smaller time interval between the photographs? explain your answer.

If two parallel light rays hit a mirror, they will not be parallel to each other after they reflect.