2007-06-24 04:33:07 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Luminous substance is that which emits light (like a heat bulb, sun, stars etc.) where as opaque substances are those that do not allow the light to pass through them. Since light does not pass through, some of it may get reflected back and the object may apear luminous by reflected light. Luminous road signs are an example. In their case, they reflect most of the light back (even the stray light of head lamps not directly in line) and thus help the motorists. They are not truly luminous but are opaque.
Moon is another example of an opaque celestial body which appears luminous but is not.
Candles, oil lamps, a coal fire, electric lamps, stars, sun .... are examples of luminous objects.
Luminous watch dials used to be painted with a mixture of radioactive materials and flourescent chemicals which emit visible light when their atoms are excited by radioactive rays.
2007-06-24 05:22:19 · answer #1 · answered by Swamy 7 · 0⤊ 0⤋
A luminous object glows as though it were bathed in light, an opaque object is impenetrable to light.
2007-06-26 14:08:15 · answer #2 · answered by johnandeileen2000 7 · 0⤊ 0⤋
luminous means that it gives off light..opaque means light cannot travel thru it.
2007-06-24 04:42:35 · answer #3 · answered by ry0534 6 · 0⤊ 0⤋
luminous - refers to objects emitting light
opaque - means that an object reflects most light and transmits very little
2007-06-24 04:45:05 · answer #4 · answered by wrflyer2001 2 · 0⤊ 0⤋