Abstract

<p>The various factors affecting conduction and convection are discussed. Ordinarily, the power carried away from a heated body by these processes cannot be calculated accurately. Two ways of measuring it are described: (1) by boiling water in a container and subtracting from the power input the losses due to evaporation and radiation; and (2) by silvering the bulb of a 500-watt tungsten-filament lamp on the outside, and then making the power input such that the average bulb temperature is the same as that of the unsilvered lamp at normal input. A similar test, but with the bulb silvered on the inside, combined with the results of test (2), gave the power radiated by the bulb. Thus, we find 8 percent of the input to a regular 500-watt lamp carried off by conduction and convection, 11 percent by bulb radiation, the rest by direct filament radiation.</p><p>Test (1) showed a conduction and convection loss of about 0.05 watt/cm<sup>2</sup> at 100°C. This exceeded the radiation loss for every surface tested except a radiator enamel (total emissivity 0.77).</p>

PDF Article

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription