I'm planing to buy infra red equipment (maybe FLIR C5 or RSpec Explorer, links below) to measure and compare the temperature of resistors and light bulbs at the same time as students measure voltage and current. Maybe even determine the melting point of tungsten...
Of course I'd like to add phyphox' light sensor to the mix.
For example, did anyone try the sensor with a infrared 10-nm filter?
03-21-2022, 08:14 AM (This post was last modified: 03-21-2022, 08:19 AM by solid.)
Hi Erik
I did not measure the light with filters but I measured the polarized light passing through a polarizer (Malus law) and I saw that telephon sensor cuts low intensity light. To the contrary SensorTag light sensor measures the light intensity correctly.
I did not measure the light with filters but I measured the polarized light passing through a polarizer (Malus law) and I saw that telephon sensor cuts low intensity light. To the contrary SensorTag light sensor measures the light intensity correctly.
You need at least 2 filters and a callibration procedure in order to determine the temperature. A nice idea of an experiment. I should try it with my interference filters.
(03-21-2022, 02:16 PM)solid Wrote: You need at least 2 filters and a callibration procedure in order to determine the temperature. A nice idea of an experiment. I should try it with my interference filters.
Thank you!
The light sensor should pick up the light from the light bulb nicely as soon as it starts to glow, and, therefore, you could maybe "force" it to just measure intensity of one wavelength ±5 nm (as the red filter I found does). Before "glow temepratures" you'd have to rely on the infra red camera.
The intensity of that wavelength could then perhaps be used to find the temperature of the tungsten filament, even if the λ-max at each temperature will become shorter as temperature increases (Wien's law).
As you'd have U*I for every light sensor value (and at low temperatures for every heat camera measurement) it should be possible to figure out the area of the emitting tungsten filament, no?
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)
(03-21-2022, 09:10 PM)Jens Noritzsch Wrote: 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:
I suppose/fear some heavy technical specs digging of the light sensor is required.