Unformatted text preview: sed of many “discrete
wavelengths.” You can see this with the plastic “grating” we supplied.
Your eye Light source Hold grating less than 1 inch from your eye. Your view through
the grating: Put light source at
left side of grating. View spectral lines by
looking at about 45o. If
you don’t see anything,
rotate grating 90o.
Lecture 4, p 13 Atomic Spectroscopy
Figure showing examples of atomic spectra for H, Hg, and Ne.
Can you see these lines in the demonstration? You can keep the grating. See if you can see the atomic
lines in Hg or Na street lights or neon signs.
The lines are explained by Quantum Mechanics.
Source for figure:
http://www.physics.uc.edu/~sitko/CollegePhysicsIII/28-AtomicPhysics/AtomicPhysics.htm Lecture 4, p 14 Diffraction from gratings
⎛ྎ sin(Nφ / 2) ⎞ྏ
IN = I1 ⎜ྎ
sin(φ / 2) ⎠ྏ
⎝ྎ 2 The slit/line spacing determines the location of the peaks (and the
angular dispersing power θ(λ) of the grating:
The positions of the principal interference maxima
are the same for any number of slits! d sinθ = mλ The number of slits/beam size determi...
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