The wavelength range of visible light is commonly considered to be approximately 390 to 700 nanometers (nm). However, there can be slight variations in the specific values depending on different sources and conventions.
The range you mentioned, 390-770 nm, is slightly broader than the typical range and may include some near-infrared and ultraviolet wavelengths that are sometimes considered to be part of the visible spectrum. The range of 380-740 nm is also commonly used, but it is a slightly narrower range compared to the conventional 390-700 nm.
The differences in the reported ranges can be attributed to several factors. First, the perception of color and the boundaries of the visible spectrum can vary among individuals. Additionally, there is no universally accepted definition of the exact wavelengths that define the boundaries of the visible spectrum.
In general, the wavelengths between approximately 390 to 700 nm are considered as the visible light range. Within this range, different wavelengths correspond to different colors. For example, shorter wavelengths around 390-450 nm are perceived as violet or blue, while longer wavelengths around 620-700 nm are perceived as red.
It's important to note that these ranges are approximate and can vary slightly depending on the context and source. However, for most practical purposes and general discussions about visible light, the range of 390-700 nm is widely accepted.