Radiation absorption

It is a known fact that suits wear light colors when it’s hot and we are exposed to sunlight. The reason is that light colors reflect more radiation they receive, than dark colors, which absorb more radiation than the first. By absorbing more radiation heat up faster, reach a higher temperature, and transfer more heat to the environment. This experience is intended to show what the relationship between the clear, as to the absorption of radiation, mainly dark colors and heat.

To realize we will expose two cans, one painted white and painted black, in the light of an incandescent bulb of 60 watts, which delivers enough heat to the environment (also can be made in the light of the sun) recording changes temperature until it is almost stable and then graph the results.

Cans

The cans are preserved, but also can be used beverage aluminum. They are painted with synthetic enamel spray and placed in a styrofoam container to capture the heat from the bulb and to prevent drafts affecting the temperature of the cans. Wires connect thermometers Dallas DS1820 with Arduino.

Thermometers are made only by the integrated (see picture below) and are not in contact with the can, so to measure the air temperature inside.

DallasThe thermometers transmitted by Dallas 1-Wire protocol by DQ pin (pin 2) and the other two pins are for ground and Vcc.

The only requirement is a resistor between pin 4.7KOHMS data and Vcc.

Below is the connection diagram.

 

 

 

 

 

Thermometers-Esquema_esquema

At the start of the experiment we ensure that both cans are at the same temperature. We place the lamp equidistantly cans and light it. Data recording lasted 42 minutes and the resulting graph is this:

chart_1

in which clearly note the rapid increase in temperature for canned black on white and the highest value achieved. Thus, black can be heated more than the white and thereby the air heated in its interior, whose temperature is the one recorded.

So our body feels warmer when inside a dark clothing, which in clear.

Here I leave the connection diagram to the Arduino:

Thermometers-Proto_bb

And the Arduino sketch, for which we use the libraries OneWire and DallasTemperature from here :

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