What they look like

This sensor is used to measure light intensity in units called lux

Note: The Lux is a derived unit based on lumen, and lumen is a derived unit based on candela.

One lux is equal to one lumen per square metre, where 4p lumens is the total luminous flux of a light source of one candela of luminous intensity:

As with other SI units, SI prefixes can be used, for example a kilolux (klx) is 1000 lux.

One unit of Lux is the equivalent of the light from a candle at a distance of 1 metre.

       50 Lux = a 60 watt bulb at a distance of 1 metre
     100 Lux = a 100 watt bulb at a distance of 1 metre
     500 Lux = Florescent light
   1000 Lux = Overcast Day
20,000 Lux = Winter Sun
80,000 Lux = Summer Sun

How the sensor works

The sensor uses a silicon photodiode. It produces a voltage which is proportional to light intensity.

Where it can be used

• Ecology studies
• Perform inverse square light intensity experiments using a point source of light
• Conduct polarized filter studies
• Demonstrate the flicker of fluorescent lamps and other lamps and hence measure the frequency of an AC supply
• Carry out solar energy studies
• Investigate reflection and refraction
• Study light intensity in various parts of a house or school
• Use it as part of an investigation of plant growth to measure light intensity