Exploring the Intensity versus Distance Profile of Light Emitted by a Household UV Bulb

We studied the intensity versus source-to-sensor distance profile of the UV radiation emitted by a household UV bulb. Quite often, in an introductory college physics laboratory, there is no laboratory equipment capable of detecting and measuring UV radiations. We built a custom experiment set up using a GUVA-S12SD sensor and found that the UV intensity (y) decreases as the source-to-sensor distance (x) increases in accordance to the power law, . Our experimentally determined power-law exponent deviated from the theoretical inverse-square exponent of -2.0. We systematically explored the role of UV bulb’s geometry and its enclosure, in explaining the deviation from the inverse-square law behavior. We also present a theoretical model that confirms our experimental findings of the power law exponent.