The effect of radiation on the human body
The epidermis has a surface of about 2 m², is in all respects a cover that acts as a physical barrier against the outside and at the same time supports the thermoregulatory system (temperature-sensitive receptor cells), blood vessels and sweat glands. Radiation hitting the epidermis will have different reactions according to the size and the wavelength. Instead of the light, shortwave x-rays pass the body, large doses are harmful.
With increasing wavelength decreases the depth of penetration, if we radiate the epidermis with infrared-C this is absorbed completely in the outer layer, where are located the thermal receptors which react by sending to the central nervous system the impetus that allows increased circulation and sweating.
The ultra-violet and x-rays penetrate deeper layers of the epidermis causing tissue damage as heat receptors are located at outer layer and don’t realize the rising temperature may be risking deep sunburn in the skin.
Transmission of infrared radiation
The spectrum of infrared and ultraviolet are invisible. From the physical point of view infrared consists of electromagnetic waves.
The wavelengths of infrared-A and B and ultraviolet-A and B are harmful to the skin. The danger is the depth of penetration through the skin, with the impossibility of action of our thermal earners in that reside in an upper layer.
If our thermal earners feel excess heat on the body they work by sending a pulse to the brain and this allows us not to burn. Other defense are the eyes that allow us to evaluate the light intensity in the range of between 0.78 ?m and 0.38 µm.
The wavelength of infrared-C issued by Celsius (panel, electric towel warmer, infrared sauna, heated towel warmer rail), is healthy for the skin, not penetrating deep active leaves our defenses that are in the papillary layer. With heating panels Celsius you cannot accidentally burn your skin, being issued IR-C only 7 ?m to 11 ?m.
The transmission and absorption of heat from the source to the consumer can be used in various ways. The human body can heat by means of heat carrier (water, air, etc), or by radiation that allows the transport of energy in vacuum spaces, like in nature to the solar radiation. The Sun’s rays spans a wide range of wavelengths, only part of the spectrum comes to us, the other harmful ultraviolet parts are restrained and attenuated gy the atmosphere.
Radiation emission and reception
Every subject, exists in the universe absorbs and emits radiation in varying quality, influencing structure is it solid or liquid or gaseous form but also the smoother surface reflect more and the rougher surface instead absorb more; This involves the heating of material.
total radiation = (a + r + d = 1)
reflected (r), absorbt (in) and transmitted (d)
absorption + transmission + reflection = total radiation
In accordance with the Stefan-Boltsmann law: full emissive power of the blackbody is proportional to the fourth power of temperature through a constant,
example: = ??4, in W/m2, s is issuing constant, ? = 5.67 ? 10-8 (m ² K4). The radiant energy emitted is not equally distributed, has a maximum characteristic and can be calculated according to the law of the move.
The law of displacement by Wien
The product of the wavelength and the maximum specific emission is constant. Higher temperatures mean shorter wavelengths and the emission maximum shifts with increasing intensity toward shorter wavelengths which is = ?max ? ? = 2896 K. ?max wavelengths are here in micrometers (?m) and ? (absolute) temperature in kelvins (K). The maximum emission of a body with a surface temperature of 37° C = 310 K of ? = 9.3 ?m wavelength (2896: 310 = 9.342).
A human body has a temperature of 37° C; in an environment where the temperature is lower than cools by radiating heat to the environment, by Convention, breath, secretion and radiation.
The old bulb is more a heat radiator that a light source, in fact the spiral reaches about 2300 K (about 2000° C) which corresponds to a wavelength of 1.25 ?m; this wavelength is outside the visible light range extending from 0.380 to 0.780 ?m, then only the portion of the spiral cooler emits the light that we see, it has a performance, as luminous efficiency in relation to electricity absorbed and converted into light energy, of 5%.
A physical body that emits the radiation it absorbs well with equal ease, this also happens with human tissue. The epidermal absorption characteristics mentioned previously are transformed into perception of heat in comparison to radiation received.
The human body has its own energy balance and draws the most power, which is converted by the digestive system and then forfeited as energy per then merge into the bloodstream.
Radiation sources for heat emission
According to the second principle of thermodynamics, heat spreads from a hot body to a cold. Each heat source with surface temperature higher than that of the body,is perceived as heat. By this, of course, also depends on distance from the heat source. There is, for example, the heat of a stove that reaches 100° C in a distance of one meter from us, than the Sun has a surface temperature of 6000° C but it is 150 million kilometers away.
In the 20 ‘s-30 ‘s were carried out experiments with infrared radiation by means of carbon filament lamp, incandescent, annealing house gas radiators and brought to a temperature exceeding 2500° C, then in the years ‘ 50-‘ 90 went to bars in quartz and ceramic by temperature down to 300-400° C (in what was deemed a good result, despite the danger of direct contact).
Recently it has developed the technology of electric heating Celsius with which it was possible to approach the wavelength healthier and strong of 5 ?m. The perception of heat is highest, this has been possible thanks to a thin film of noble materials appropriately shaped, assembled and fed. This thin film inserted into heater Celsius, manages to give off in extreme safety 8.5 ?m Infrared waves with a low energy commitment.