Lower Light Bills

New Zealand Listener, Volume 5, Issue 117, 19 September 1941, Page 5

Lower Light Bills

EOPLE who have. not thought deeply enough sometimes point reproachfully to the low efficiency of the modern incandescent lamp. Only 9 per cent, of the energy supplied is converted into light.

The rest is wasted as heat. They may have heard claims that the efficiency of a flashing firefly’s light emission is 96 per cent. They conclude that scientists, for all their work and talk, are still very far from approaching Nature’s methods for light production, . Like many good stories, this one is more interesting than true. That there is scope for vast improvement in the efficiency of lamps is undoubtedly true. Let us rejoice that there is a possibility that our future light bills may be further reduced. The figure quoted for the firefly’s efficiency is based on an unjustifiable assumption and is certainly too high. Yet we may learn something from*the comparison. The light from fireflies and glow-worms is approximately yellowgreen, to which our eyes are most sensitive. Also they are apparently "cold" sources: By years of arduous toil, physicists have discovered some of the secrets of atomic structure. One consequence-by no means the most important-has been the development of a new type of light source. This comes nearer to the firefly than previous ones. By judicious sharp-shooting with electrons the atoms of a cool vapour are caused to emit light. In this process little energy is wasted. _-(" Atoms in Action to Serve Mankind,’ Dr. C. M. Focken, 4Y A, September 3.)