Planck and the light sensor

[Erik Josefsson]

Please note that the “quality” (including rate and resolution) heavily varies between smartphones and infrared might get filtered (for some time, it was not possible to see the light of a remote on iPhones, for instance – however, there is no interface for the light sensor anyway: https://phyphox.org/faq/#faqIosLight)

Yes, you would have to know what sensor your phone has. In my case GT-I9300, but thanks to the excellent sensor database I can find out more about what the sensor can and cannot do: https://phyphox.org/sensordb/

Name
CM36651 Light Sensor
Vendor
Capella Microsystems
Range
121240 lx
Resolution
1.0 lx

The question here is whether that sensor can add information and/or measure data in the educational context of heat radiation and planck curves.

Clearly the CM36651 Light Sensor will "see" a fully shining 3.5 V small light bulb very well, but what if the light was filtered so that only 670 ± 5 nm comes through?

And if so, would that signal say anything meaningful in relation to the light bulb power (P=U*I)?

According to this fine graph just 0.5% of the total radiation power would come from 670 ± 5 nm at T=3000 K:

https://www.geogebra.org/m/EtCNHst7

and even less would show as signal if the sensor indeed uses the Luminous efficiency function.

But it would be nice to know :-)

Best regards.

//Erik