Humans can only naturally see when light is in the visible spectrum with wavelengths between 400 and 700 nanometers. Light also has a frequency, which is how many waves pass a certain point in a certain amount of time. Visible light has a frequency between 430 and 750 trillion hertz per second. read more
A light bulb is a simple apparatus that converts electric energy into light energy. The law of conservation of energy says that energy can neither be created nor destroyed, it simply changes form. A light bulb is able to take the electricity supplied to it and change its form into something that can be used for illumination. read more