Violet As the name of a color, violet (named after the flower violet) is used in two senses: first, referring to the color of light at the short-wavelength end of the visible spectrum, approximately 380–420 nm when indigo is recognized as a distinct color, or more commonly 380–450 nm[3] (this is a spectral color). Second, violet may refer to a shade of purple, that is, a mixture of red and blue light, and not a spectral color (see a discussion of the distinction between violet and purple). Spectral violet is outside the gamut of typical RGB color spaces, and although it can be approximated by that color shown below as electric violet, it cannot be reproduced exactly on a computer screen.
Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV. It is so named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet.
UV light is found in sunlight and is emitted by electric arcs and specialized lights such as black lights. As an ionizing radiation it can cause chemical reactions, and causes many substances to glow or fluoresce. Most people are aware of the effects of UV through the painful condition of sunburn, but the UV spectrum has many other effects, both beneficial and damaging, on human health.
A tremor is an involuntary,[1] somewhat rhythmic, muscle contraction and relaxation involving to-and-fro movements (oscillations or twitching) of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, face, head, vocal cords, trunk, and legs. Most tremors occur in the hands. In some people, tremor is a symptom of another neurological disorder. A very common kind of tremor is the chattering of teeth, usually induced by cold temperatures or by fear. Tremor can be a symptom associated with disorders in those parts of the brain that control muscles throughout the body or in particular areas, such as the hands.