EM Spectrum Flashcards
Young’s double slit eqn vs single slit eqn
deltax = mlambda = dsintheta at constructive points vs deltax = mlambda = wsintheta at destructive points
If d dec, theta inc b/c m*lambda stays the same
Young’s double slit showed that light acts as a wave
Know the conditions of constr vs destr interference regarding lambda and pi shifts
cons: lambda, 2lambda, 3lambda, 4lamda etc; des: lambda/2, 3lambda/2, 5lambda/2, etc. If there is a pi shift –> switch the conditions
Is there a pi shift during reflection?
Yes, only when it reflects off a slow medium
What does deltax represent for double slit vs thin film interference?
dsintheta vs 2t
What happens to freq of a wave when it goes thru diff media?
stays the same
Know the eqns about v and n to find thin film lambda
Know em. Too complicated to write here
What’s the rule of thumb when looking for thin film lambda?
if the wave is going to a slower medium –> look for v, n or lambda ratio < 1; if the wave is going to a faster medium –> look for v, n or lambda ratio > 1
Formula for energy of photon
E = hf
h = Planck’s constant (6.626E-34 Js) f = freq in Hz
Photoelectric effect. Does freq or intensity affect this phenomenon?
When a photon hits an e- on a metal surface in a vacuum, the photon = absorbed and that e- gets kicked off the surface. The liberated e- will produce a current
Energy of ejected e- depends on freq, not intensity. Stronger intensity of photons —> MORE e- kicked out (all the ejected e- just had the same KE)—> stronger current
It takes all or none energy, no portions
Showed that light acts both as waves and particles
de Broglie wavelength
Lambda of e- = h/p
p is momentum
Speed of light formula
c = f*lambda
What happens when light hits a thin film?
Some light could be reflected, other light could refract thru
Why are EM waves transverse?
Cuz their oscillating electric and magnetic field vectors = perpendicular to propagation. ONLY TRANSVERSE WAVES HAVE POLARIZATION - a property of a wave when it can oscillate w/ more than one orientation
Blackbody
An ideal absorber of all wavelengths of light —> it would look completely black
Visible light spectrum range
400 (violet)-700 (red) nm
What happens to central maximum when slit becomes narrower?
Central maximum becomes wider since light waves can spread out even more
Spherical aberration vs chromatic aberration vs dispersion
Blurring of periphery due to inadequate reflection of parallel beams at edge of mirror or inadequate refraction of parallel beams at edge of lens vs dispersive effect within a lens vs when various wavelengths of light separate from e/o (ex: white light splitting into different colors thru a prism; this can happen during diffraction or refraction)
Plane/linear polarized light vs circular polarized light
Light in which electric fields of all waves = oriented in same direction vs oriented in continuously changing directions (helical)
What’s the relationship b/w energy and stability? vs Energy and freq?
Inverse vs direct
Continuous vs absorption vs emission line spectra
White light contains all wavelengths of light vs shine a light source on a ground state sample —> dark bands = wavelengths that are absorbed by sample in ground state (colors mean they’re transmitted thru prism) vs excited sample being its own light source —> bright bands = wavelengths that are emitted by sample in excited state
Wave-particle duality
Light and matter behave like both waves and particles
Max and min KE to eject e-
K = hf-W
K=max energy to eject e-
W=min energy to eject e-; W (aka work function) = hf_T where f_T = min freq to eject e-, an all or nothing response
How to find specific rotation aka [alpha] vs finding enantiomer excess?
Observed alpha/(conclength in dm) vs (observed alpha100)/[alpha]
Diffraction
Bending and spreading of light when passing thru a narrow slit
rotational transitions vs vibrational transitions vs electronic transitions vs photoionization
caused by absorption of microwaves, produces heat vs caused by absorption of IR waves, produces heat vs caused by absorption of vis light AND lower end of UV spectrum, product heat or release photons in visible range (fyi: H2O = transparent to vis light, so it doesn’t release photon in visible range) vs caused by absorption of higher end of UV spectrum, x-rays, or gamma rays
