Introduction

            The rotating mirror technique, as described by Hinshaw¹, is one that was conceived to separate a very quick event over space and time across a film so that distinct stages of the event could be observed and analyzed separately. This same technique was used in this experiment to spatially and temporally separate stages during which a BB fired at high speed penetrated a light bulb and compromised the normally airtight environment. Light bulbs are comprised of a tungsten filament that rests on a glass mount, all of which is surrounded by the airtight glass “bulb.” The near vacuum seal provided by the glass bulb prevents combustion of the tungsten filament that would normally occur in the presence of ambient oxygen². Furthermore, the bulb is filled with the inert gas argon and coated with silica powder to prevent loss of the tungsten filament and to diffuse the light produced³. The rotating mirror method was used to evaluate the decreasing intensity of the bulb’s filament after the environment surrounding it had been compromised. This was done through use of computer-controlled timing methods, a BB gun, and extensive use of electronic timing devices (annunciators and phototransistors) to correctly fire and photograph the dimming filament over time.