1. Torrieri Andrea
5°E
and everything you need to know about
elecromagnetic wawes.
The electromagnetic
spectrum

2. The electromagnetic
spectrum
Is the set of all the possible
frequencies of the
electromagnetic radiation.
Since all e.m. waves move at
the speed of light, it's the
frequency to determine the
wavelength.

3. Electromagnetic waves
classification
E.m. waves are separated into groups,
each characterized by a frequency (so
also a wavelength) and a typical use of
that particular range of waves.
These characteristics give the name to
respective group.
electromagnetic
specrum classification

4. In this case they're used to transmit audio informations,
with infrastructures similar to those used for television
(sometimes with the same infrastructure)
Radio
Radio waves are used to trasmit audio and video
informations in real time thanks to a network of
antennas (also installed in our houses ) and repeaters.
Television
A radar uses the refraction of radio waves to
determinate the position and the speed of objects in
particular conditions where it is difficult to use the visible
light to see. Also microwaves are used by radars.
Radar
Radio waves have the lowest
frequency of the spectrum (after
e.m. waves generated by electric
lines) and they're used in different
fields, with the aim of transmitting
information.
Radio waves

5. The most widespread use of
microwaves is the microwave
oven. This household appliance
uses a magnetron to generate a
e.m. radiation which causes the
hydrogen atoms of food's water
molecules to move very
quickly.The fricton beetween them
generates heat which heats the
food.
Microwaves
a picture of a
microwave oven

6. we can see the effect of the microwaves
generated by the oven by heating a chocolate
bar with it.
We can clearly see that the chocolate starts to
heat in particular points where we have a ridge
or a depression of the wave.
If we multiply the distance beetwen these two
point by 2 and by the frequency we obtain the
speed of light
Microwave and chocolate experiment
Experiment picture

7. Infrared radiation
The infrared radiation is close to the red visible
light in the e.m. spectrum. It is emitted by the
molecular thermal agitation of bodies and it is
also easy to absorb causing heating. We can
use special cameras and sensors to "see" this
radiation and identify the temperature of
distant objects.
Infrared are mainly used to transmit TV's
controllers signal.
A
infrared
camera
picture

8. The visible light
Visible light spectrum
The visible light is the portion of the e.m. spectrum which we're able to see.
The colour of the light that we see is determinated by the wavelength

9. The ultraviolet radiation is invisible to us,
but there are some objects which absorb
the UV radiation and emit another e.m.
radiation included in the spectrum of
visible light. this phenomenon is called
phosphorescence.
Ultraviolet

10. Ultraviolet radiation
Sunlight is composed by 10% of UV rays,
which are responsible of many types of
tumors.
Earth's shield against UV is the
ozonosphere, an atmosphere's high
layer which is being damaged by
humans activity during the years.

11. X-rays
X-rays are generated when electron beams are
stopped by matter. The most known
application of them is in the medical field to
obtain images of internal parts of the body
thanks to their ability to penetrate some
materials. To see the image, X-rays are
captured on plates made out of plastic and
silver.
a X-ray image

12. Gamma rays
Gamma rays have the shortest
wavelength of the spectrum, so
they have an incredible penetrating
ability.

13. Dark matter
The nature of dark matter, the substance that accounts
for more than 85% of all matter in the Universe, remains a
mystery. One popular hypothesis is that dark matter
consists at least partially of hypothetical particles called
axions or axion-like particles.when flying through a
magnetic field or close to charged particles, a beam of
axions could actually transform into photons or vice versa.

14. This special property leads to an intriguing possibility,
where axions could be created during the explosion of
a massive star at the end of its lifetime, an event
commonly known as a supernova.In the core of the
explosion, ions and protons are densely squeezed
together, allowing energetic photons, called gamma
rays, to transform into axions. In this ghostly axion
form, they can quickly escape the dense core and
slowly return to gamma-ray form on their long path
through the magnetic fields in space.
Supernova

15. Upon reaching Earth, the resulting short
burst of gamma rays could be detected
with the Large Area Telescope (LAT) on
board the Fermi satellite, which constantly
scans the entire sky for gamma rays and
sees roughly 20% of the sky at any given
moment. The challenge is to know when
exactly to look for the burst, which,
according to theory, is only tens of seconds
long.
Large area telescope

16. A new study uses the wealth of data collected with the Fermi LAT to
search for the axion-induced bursts by correlating it with, for the first time,
the results of dedicated supernova surveys. These surveys, which use
traditional optical telescopes, detect hundreds of supernovae each year.
By modeling the fading glow of the explosions, from the Erlangen Center
of Astroparticle Physics and Tanja Petrushevska from the University Nova
Gorica were able to make predictions for the time window of the
explosion and search for the expected
Large area telescope

17. FINE
Torrieri Andrea
5°E