Light is part of the electromagnetic spectrum, which ranges from radio waves to gamma rays. ... Light can be generated by the matter or a photon of light can interact with the energy levels in a number of ways. We can represent the energy levels in a diagram known as a Jablonski diagram. flashlight (often called a torch outside North America) is a portable hand-held electric light. The source of the light often used to be an incandescent light bulb (lamp) but has been gradually replaced by light-emitting diodes (LEDs) since the mid-2000s. A typical flashlight consists of the light source mounted in a reflector, a transparent cover (sometimes combined with a lens) to protect the light source and reflector, a battery, and a switch. These are supported and protected by a case.
The invention of the dry cell and miniature incandescent electric lamps made the first battery-powered flashlights possible around 1899. Today, flashlights use mostly light-emitting diodes and run on disposable.
