=Introduction= A flashlight, (US) torch, or torchlight (UK) is a portable hand-held electric light. Formerly, the light source typically was a miniature incandescent light bulb but these have been displaced 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, all enclosed in a case.
=Challenges= Working without light or even without enough light can present serious challenges.
=Approaches= LEDs make efficient use of power from batteries for production of light.
=References=