Hvor meget lumen?

[RunesS_phpbb3_import15750]

hannover_dk Skrev:

RunesS Skrev:

BobT Skrev:Var det radium, med en halveringstid på 1602 år, ville det vel idag være ret tydeligt at se om natten.

Jeg har set mange "døde" radium skiver. Jeg mener at huske, at det er fordi det lysende stof, som holdes i gang af det radioaktive udfald, forgår.

ikke umuligt. det som lyser er vel som oftest fosfor
vh

Har læst lidt op på det...

Citat:...was made with a mixture of radioactive radium and zinc sulphide. The zinc sulphide "fluoresces" (glows brightly) when hit by radiation from the radium. This paint glowed all the time, day and night, without needing exposure to sunlight, and continued to glow for years on end, even when stored away from the light in a drawer. However, after some time, maybe twenty to fifty years, the zinc sulfide is worn out or destroyed by the radiation from the radium, so the paint no longer glows in the dark - but the radium has hardly changed and is still there, emitting radiation.