A light source emits light with dominant wavelengths in the range of 650 to 690 nm. what is the principle color of light emitted by the source?

Please see below as the answer is self-explanatory.

Explanation:

The visible range extends roughly from 400 nm (violet) to 700 nm (red).Below the violet is the ultra-violet spectrum (with higher energy) and above red, we have the infra-red spectrum.The wavelengths in the range of 650 to 690 nm have red as the dominant color.

Neptune is the eighth planet from the sun. it was the first planet to get its existence predicted by  mathematical calculations  before it was actually seen through a telescope on sept. 23, 1846. irregularities in the orbit of  uranus  led french astronomer alexis bouvard to suggest that the gravitational pull from another celestial body might be responsible. german astronomer johann galle then relied on subsequent calculations to   spot neptune via telescope. previously, astronomer galileo galilei sketched the planet, but he mistook it for a star due to its slow motion. in accordance with all the other planets seen in the sky, this new world was given a name from greek and roman mythology — neptune, the roman god of the sea.

Kinetic energy = 1/2mv^2. since the mass is constant we can form a ratio of it's kinetic energy at 60 divided by that at 30 to see ke(60)/ke(30) = +(60^2)/30^2). this may be said to 300% increase.