Why is the Sl measurement system so important to the scientific community

The two most prominent wavelengths in the light emitted by a hydrogen discharge lamp are 656 nm(red) and 486 nm (blue). light from a hydrogen lamp illuminates a diffraction grating with 520lines/mm , and the light is observed on a screen 1.5m behind the grating. part a what is the distance between the first-order red and blue fringes? express your answer to two significant figures and include the appropriate units.

The sun generates both mechanical and electromagnetic waves. which statement about those wave is true?

The slope of a velocity time graph over any interval of time gives the during that interval