EM Spectrum

Question 1

Young’s double slit eqn vs single slit eqn

Answer 1

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

Question 2

Know the conditions of constr vs destr interference regarding lambda and pi shifts

Answer 2

cons: lambda, 2lambda, 3lambda, 4lamda etc; des: lambda/2, 3lambda/2, 5lambda/2, etc. If there is a pi shift –> switch the conditions

Question 3

Is there a pi shift during reflection?

Answer 3

Yes, only when it reflects off a slow medium

Question 4

What does deltax represent for double slit vs thin film interference?

Answer 4

dsintheta vs 2t

Question 5

What happens to freq of a wave when it goes thru diff media?

Answer 5

stays the same

Question 6

Know the eqns about v and n to find thin film lambda

Answer 6

Know em. Too complicated to write here

Question 7

What’s the rule of thumb when looking for thin film lambda?

Answer 7

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

Question 8

Formula for energy of photon

Answer 8

E = hf

h = Planck’s constant (6.626E-34 Js)
f = freq in Hz

Question 9

Photoelectric effect. Does freq or intensity affect this phenomenon?

Answer 9

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

Question 10

de Broglie wavelength

Answer 10

Lambda of e- = h/p

p is momentum

Question 11

Speed of light formula

Answer 11

c = f*lambda

Question 12

What happens when light hits a thin film?

Answer 12

Some light could be reflected, other light could refract thru

Question 13

Why are EM waves transverse?

Answer 13

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

Question 14

Blackbody

Answer 14

An ideal absorber of all wavelengths of light —> it would look completely black

Question 15

Visible light spectrum range

Answer 15

400 (violet)-700 (red) nm

Question 16

What happens to central maximum when slit becomes narrower?

Answer 16

Central maximum becomes wider since light waves can spread out even more

Question 17

Spherical aberration vs chromatic aberration vs dispersion

Answer 17

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)

Question 18

Plane/linear polarized light vs circular polarized light

Answer 18

Light in which electric fields of all waves = oriented in same direction vs oriented in continuously changing directions (helical)

Question 19

What’s the relationship b/w energy and stability? vs Energy and freq?

Answer 19

Inverse vs direct

Question 20

Continuous vs absorption vs emission line spectra

Answer 20

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

Question 21

Wave-particle duality

Answer 21

Light and matter behave like both waves and particles

Question 22

Max and min KE to eject e-

Answer 22

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

Question 23

How to find specific rotation aka [alpha] vs finding enantiomer excess?

Answer 23

Observed alpha/(conclength in dm) vs (observed alpha100)/[alpha]

Question 24

Diffraction

Answer 24

Bending and spreading of light when passing thru a narrow slit

Question 25

rotational transitions vs vibrational transitions vs electronic transitions vs photoionization

Answer 25

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