Im not completely sure but It might be Cycling of Matter
Neils bohar proposed his atomic model in 1913.
He describe that's electron travel in a circular orbit surrounds the neuclus of an atom.each orbit has quantized energy and size. Energy is transmitted when an electron jumps from one to other orbit near to nucleus.and it absorb energy when it jumbs away from nucleus.he also said that these electrons are restricted to fixed orbits. In excited state of electron, they absorb or emitt photon with specific wavelength.
X-Ray used to Take images of teeth and bones.
Ultraviolet night vision goggle
