conversely the light guide 302 may contain scattering particles along its entire length but be covered along selected segments by a light blocking material in still another alternative light is generally confined within the light guide 302 by tir and clamping a track light over the light guide 302 distorts the light guide sufficiently to cause light emission the light guide 302 may also carry power and via inductive or capacitive coupling provide power to the track heads alternatively a slot or other aperture in the light guide 302 may provide for an electrical power connection to the track heads the track 304 may be for example a flexible and electrically conductive metal band and the light guide 304 may be wholly or partially covered by clear flexible plastic that allows light to be transmitted therethrough another track lighting system 400 that includes a track 402 and a track head 404 is illustrated in fig4 a light source 405 slidably disposed on the track 402 may be releasably retained in a position 406 at the end of track 402 in a position 408 within the track 402 or in a position 410 within the track head 404 for example the light source 405 may include one or more led lights and the led lights may include leds of different colors.