6. When the body is heated it
emit radiation called
“Thermal radiations”.
Our body is hotter it is also
emit thermal radiation
7
7. This effect is not unique to
humans. All objects with a
non-zero temperature give
off thermal radiation. And
because a temperature of
exactly absolute zero is
physically impossible, all
objects give off thermal
radiation.
8
8. “Thermal radiation” is all the
electromagnetic waves given
off by an object because of its
temperature, and includes
radio waves, infrared waves
are only one part of thermal
radiation.
9
9. Why we can’t see the
radiations which our body
emits?
10
10. “
”
The nature of radiation
depends upon the
temperature
At high temperature?
At low temperature?11
11. a body
emits radiations which are of
shorter wavelengths and higher
frequency. The radiation which
have shorter wavelength can see
with human eyes.
12
12. a body
emit radiation which are of longer
wavelength and low frequency. The
radiations with longer wavelength
can’t see with human eyes.
13
13. Human body have low temperature so
the body emit radiations which have
longer wavelength and low frequency that
is why we can’t see the human radiations
14
14. Humans give off thermal
radiations which are
mostly infrared radiation.
Infrared radiation is
electromagnetic
radiation with a
frequency lower than
visible light
15
15. Infrared radiations have low
frequency then the visible light and
low frequency can never detected by
human eyes. It can be detected by an
infrared camera.
16
16. The amount of thermal radiation emitted
by an object depends on its surface
temperature, area and characteristics.
Different people at different times give off
different amounts of radiation. But these
differences just indicate who is hotter, and
not who is fatter, taller, sadder, or more
saintly.
17
17. The wavelength of infrared radiation is
between 0.75 to 1000 micron (1 micron = 10-
6 meters) .
Most of the radiation emitted by human body
is in the infrared region, mainly at the
wavelength of 12 micron.
18
18. All the things in the world emit different types of
radiations as see in the following picture.19
Most of them are invisible to the human.
19. The advantage of infrared radiations
emit by body:
We can see the image of
body at night.
We can use it for security
purpose.
20
20. Other radiation has an
effect on the human body
It produced cancer in human body.
21
21. Even when exposed to radiation, the
human body is able to repair itself.
22
22. Radiation protection is necessary, because
radiation is all around us, in the air, the water,
the food we eat. It causes us to feel unwell,
and it can contribute to the eventual onset of
disease. That’s why we need effective ways
of protecting ourselves from this
bombardment.
23
23. Nature has provided the
most effective means to do
this using gemstones and
precious metals. But we
need to know which ones
to use and how to use
them, and how to keep
them clean, so they retain
their effectiveness.
24