Gases emit different…
Colors
Emission
Downward transitions produce a unique pattern of emission lines. When electron make a transition from higher energy state to a
lower energy state, then the difference in energy will be emitted as
a photon = emission.
Energy of photons
Difference in energy states
Delta E=hf
Absorption
Atoms can absorb photons with those same energies, so upward transitions produce absorption lines. If the energy of the incident photon matches the
energy difference between two state, the it is possible
for the electron to absorb the photon. In this case the
electron will make transition to higher energy state=
absorption.
Absorption lines
These lines are formed when the
intervening cool gas absorbs certain wavelengths
(colors) from the original beam of light. The
absorption lines appear at precisely the same
wavelengths as the emission lines that would be
produced if the gas were heated to high temperatures.
Luminosity
Measure of the output rate of energy radiation in watt.
Inverse square law
Light source spreads light in every direction. The
intensity of light I, will decrease with distance d or r.
