Illuminance and Intensity of Light.

1). According to its package, a 100 watt light bulb emits 1140 lumens. For simplicity, assume the bulb provides isotropic illumination and ALL its emission is at 555 nm. A video camera is advertised as having "0.2 lux sensitivity", meaning it can record objects which receive at least this illuminance. In a dark room with no other light source, how far away from the light bulb could an object (for example, a white card), be, and still receive just sufficient illumination to be detected by the video camera (assuming normal incidence)?

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Solution Summary

The maximum distance of the camera from the object is calculated when the minimum illuminance and the power of the source is given.