The Lux Capacitor measures illuminance (lx) at a consistent angle.
Website for download: https://play.google.com/store/apps/details?id=appinventor.ai_michael_pollock100.LuxCapacitor
Full description:
The Lux Capacitor allows you to measure illuminance at a consistent angle by showing when the Android device is level and what the illuminance (lx) is at this angle. A red ball displayed on the screen serves the role of a traditional bubble on a level tool, moving its position based on how far the device is titled in any direction (in terms of pitch and roll). When the device is held at a level angle then the ball will be in the center of the screen and turn yellow.