Safety of Physical Experiments Involving Resistance Heating

Abstract

This study was aimed to investigated the risk of burns due to Joule heat for experiments conducted in the field of physics at junior high schools. We examined the incandescent and LED light bulbs and a cement resistor, all of which were often used in the classes. Their surface temperatures were increased under different power consumption settings. The minimum temperature for risk of burns was defined as 70 degrees Celsius where all layers of skins would be destroyed within 2 seconds. From our experiments, it became clear that safety considerations for burns are necessary even if the power consumption of bulbs was below their rated values. Furthermore, descriptions of safety considerations in Japanese science textbooks were surveyed. The results showed that although there were many descriptions of precautions to avoid burns, only one publisher’s textbooks specified a specific time (about 20 minutes) for cooling under cold water as an essential response to burns.