Diapositiva 1 - Dipartimento di Fisica e Astronomia

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Diapositiva 1 - Dipartimento di Fisica e Astronomia
The Physics of MAGIC - INTRO
Elisa Prandini for the MAGIC-D Team
Padova, 2 November 2010
For your students
light is…
…what we observe with our eyes…
…and our telescopes…
Optical Observation: the “old” technique

The oldest technique… why?

Telescopes: lenses or mirrors?

Telescopes from Earth or Satellites

Very good angular resolution!
In physics, light
is a wave…
and a particle: the photon!
Collisions with
ENERGY
TRANSFER
Molecules, Atoms and Nuclei have
something in common
“discrete” structure  discrete emission!
Nella transizione da una shell all’altra, l’elettrone emette pacchetti
discreti di energia e.m.
And is part of the electromagnetic spectrum
1 Km
700 nm
1m
1 cm
1 mm
100 nm
1 nm
0,1 nm
400 nm
The Electromagnetic Spectrum
WAVELENGTH
FREQUENCY
ENERGY
E=hn=hc/l
Now, let’s enter in the electromagnetic
spectrum starting from the so-called
“low-energy”
The Radio Waves World
~10-8 eV

the signal is emitted and observed by antennas (oscillating dipoles)

It is the world of distant communications

Even if it is not visible with our eyes, it is an “everyday world”:
- mobile phone
- radio
- television
- microwave owen
The IR World
~1 eV

Before the RED in the e.m. spectrum

It is the world of HEAT
It is light typically emitted by warm
objects

~3 eV
The Optical World… Our World!
It is the world of objects emitting and absorbing
visible light
The X and g World
keV – MeV – GeV - TeV
The X and g World
keV – MeV – GeV - TeV
The X-rays world is not very bright: high
energies! Man can produce artificially X-rays
(atom and nucleus).

The human body doesn’t emit X-rays, the
bones simply stop them!

Hence…:
What we call “light” is part of the electromagnetic spectrum: it
has the same origin and properties of radio, microwave, X-rays
and gamma-rays. What is different is their ENERGY.


An object can emit one ore more different waves
When we study astrophysical objects we have to consider ALL
the physical phenomena that happen -> that’s why we observe (or
we try to observe) the same target in different wavelenghts
The Milky Way emission
The atmospheric extinction
PROPOSTA ATTIVITA’ DI LABORATORIO
EFFETTO FOTOELETTRICO:
• Passaggio dalla fisica classica alla fisica moderna
• Misure sperimentali e discussione teorica
• L’evoluzione dell’effetto fotoelettrico: il Fotomoltiplicatore
SEDE DI LAVORO: Polo Didattico (Via Loredan)