Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 380 to 740 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 405–790 THz.
The human eye can detect up to 700 nanometers but the range adjacent to the visible spectrum is called the near infrared and the longer wavelength part is called far infrared. The region just below the visible in wavelength is called the near ultraviolet. Hence the visible part of electromagnetic spectrum lies in between ultraviolet and infrared.
Polar molecules (with +/- charges) are attracted to water molecules and are hydrophilic. Nonpolar molecules are repelled by water and do not dissolve in water; are hydrophobic.
