physics test 3 study questions

How does an absorption spectrum differ in appearance from an emission spectrum?

absorption consists of dark lines across a rainbow background while emission consists of bright lines across a dark background

what are fraunhofer's lines?

absorption lines (dark lines) in the spectrum of sunlight

what is a spectroscope? What does it do?

an optical instrument used for producing spectral lines

what is a metastable state?

atoms are excited for a long time

have you ever seen burning of different material produce flames of different colors? why is that?

atoms of different elements produce different colors that are their characteristic patterns of frequencies

How does the difference in energy between energy levels relate to the energy of the photon that is emitted by a transition between those levels?

energy of a photon is equal to the difference in energy between levels e~f

what is the relationship between energy differences of orbit in an atom and light emitted by the atom?

energy of the emitted photon is equal to the difference in energy between the 2 orbits

in the photoelectric effect, does brightness or frequency determine the kinetic energy of the ejected electron? What determines the number of ejected electrons?

frequency determines the kinetic energy while brightness determines the number of electrons

should red or blue light be used to produce narrower spaced fringes?

fringe width is directly proportional to wavelength. Blue has smaller wavelength and therefore smaller fringe

Why do polarized sunglasses reduce glare?

light from polaroid is polarized, the intensity must be reduced, therefore reducing the glare

a blue hot story is about twice as hot as a red hot star, but temperatures of gas in advertising signs are about the same. Why ?

light in stars is incandescent, light in signs is fluorescent and fluorescent light doesn't change temperature too much

what is the difference between the primary and secondary excitation process in a fluorescent lamp?

primary excitation is when atoms collide and excited mercury gas. Secondary excitation is when UV light from mercury excites a phosphor to emit visible light

if atoms of a substance absorb UV light and emit red light, what becomes of "missing energy?"

rest energy has been converted to kinetic energy. raising the thermal energy

Is diffraction more pronounced through a small opening or through a large opening?

small opening

is diffraction more pronounced for a longer or shorter wavelength

longer

does Einsteins explanation of the photoelectric effect invalidate young's explanation of the double slit experiment?

no because light is a stream of particles guided by a wave

if measurements can show the precise position of an election, can they show precise momentum as well?

no, it can only show position by perturbing momentum

are electrons on the tip of your nose altered by looking at them?

no, they receive light from some other source and can only be altered by that

when we say electrons have particle properties, then say they have wave properties are we contradicting ourselves?

no. it depends on what we want to see

Why will an ideal Polaroid filter transmit 50% of incident nonpolarized light?

non-polarized light contains polarization in all directions

when does interference occur

on all types of waves

what is quantum light called

photon

what phenomenon distinguishes longitudinal from transverse waves?

polarization

When electrons are diffracted through a double slit, do they hit the screen in a wavelike way or particle way? is the pattern wavelike or particle like?

they arrive on screen in a wave like way but the pattern of hits is particle like

what does the psi represent?

wave funciton

we don't notice the wavelength of moving matter in our common lives. Is this because wavelengths are large or small?

wavelengths in common objects are extraordinarily small

why do radio waves diffract around buildings while light waves dont?

wavelengths of radio waves are comparable to the size of buildings, but light waves are not

what evidence is there for the claim that iron exists in the cool outer layer of the sun?

when a spectrum of the sun is compared with the spectrum of the element of iron, the iron lines overlap and match the Fraunhofer lines

when does light behave as a wave? when does it behave as a particle?

when it travels from source to target, it behaves as a wave. if it is emitted by a source or absorbed by a detector, it behaves as a particle

according to de Broglies model, how many wavelengths are in an electron wave in the first orbit? second?

1st orbit has 1, 2nd orbit has 2

what percentage of light is transmitted by 2 ideal polaroid, one on top of the other with axes alighted? with axis at right angles?

50% if aligned, 0% if at right angles

Consider just four of the energy levels in a certain atom, as shown in the diagram. How many spectral lines will result from all possible transitions among these levels? Which transition corresponds to the highest-frequency light emitted? To the lowest-frequency light emitted?

6 lines are possible. n=4 to n=3 is the lowest frequency and n=2 to n=1 is the highest

how is the energy of a photon related to its vibrational frequency?

energy is proportional to the frequency. E=hf

ultraviolet light causes sunburns but visible light of greater intensity doesn't. Why?

More energy is associated with each photon of UV light

how is peak frequency of emitted light related to the absolute temp of its incandescent source?

Peak frequency is proportional to absolute temperature. f=T

why is ultraviolet light, but not infrared light, effective in making certain materials flourescent?

UV has higher energy than infrared light

why is UV radiation capable of producing skin cell damage while intense visible radiation is not?

UV photons carry more energy

according to Huygens, how does every point on a wavefront behave?

as a source of secondary wavelets

if you see a red-hot star, you can be certain its peak is in the infrared. Why?

because the frequency of red is 4x10^14th and that is in the infrared zone

since absorbing gas re-emits the light it absorbs, why are there dark lines in the absorption spectrum

because the re-emitted light is over a spherical 360 degrees, not all in 1 direction

why wont a very bright beam of red light impart more energy to the ejected electron than a feeble beam of violet light?

because violet light photons have higher energy than red light photons. It has nothing to do with brightness

how does treating the electron as a wave instead of a particle solve the riddle of why orbits are discrete?

by treating it as a wave, electrons move in its orbit as a wave. The radius and angular momentum are discrete values which makes the orbit discrete

Why are interference colors primarily cyan, magenta, and yellow?

destructive interfering colors are primarily red green and blue, so we find their compliments on a soap bubble

when gas glows, discrete colors are emitted. When solids glow, they smudge. Why?

emitting elections interact with nearby atoms in a solid. In gas, there are fewer atoms nearby

in f~T, what do the letters represent

f = peak frequency of emitted light T = temperature

what will plain waves incident on small openings do?

fan out instead of continue as plain waves

what is the difference between fluorescence and phosphorescence

fluorescence involves transition that do not involve a change in electronic spin and are short lived. Phosphorescence involves a change in spin and are longer lived.

why will light pass through polaroids when axes are aligned but not when they are at right angles

if aligned, the first axis polarizes and it passes through the second, but if not aligned it cannot pass through

Why may an ideal polaroid filter transmit anything from zero-100% of incident polarized light?

if polarization is parallel to the axis of the polarizer, it would transmit 100%, if perpendicular, it would transmit 0%

what causes spectrum of colors seen in gas splotches on a wet street?

interference takes place from waves reflected by the top and bottom surfaces of the gas layer

when are quantum uncertainties significant?

in measuring an electron

how are the rings of film on oil or gas similar to those on a contour map?

in the interference of thin film, different colors form complete rings @ the location where thickness is uniform

how are interference fringes of light like sound from a speaker?

intensity of fringes vary in different locations at some distance from 2 slits that emit waves with a constant phase difference

which explains the photoelectric effect? particle nature or wave nature? Which explains the discrete levels in Bohr's model of the atom?

particle nature explains photoelectric effect wave nature explains discrete levels of Bohr's model of the atom

how does the amplitude of a matter wave relate to the probability?

probability: psi ^2 matter wave: psi

how does probability density differ from wave function

psi^2 gives the chances of finding a particle at a specific location and a specific time. Wave function represents the possibilities that can occur in a system

When ordinary light is incident at an oblique angle upon water, what can you say about the reflected light?

reflected light will polarize parallel to the surface of the water

what is the difference between monochromatic light and sunlight

sunlight has a wide range of frequencies and wavelengths. Monochromatic light only has one wavelength and frequency.

how does the probability cloud in a hydrogen atom relate to the orbit described by Bohr?

the average distance of the electron from the nucleus fits the orbital radius of bohr

what did thomas young demonstrate?

the interference effect by directing light through 2 pinholes

An orbit in a distinct path vs an atomic orbit spread over a volume of space. what do these have in common?

there is a finite probability that an electron can be found in orbits and orbitals

what is the difference between E~f and E=hf

this means energy is promotional to the frequency of radiation. E~f is qualitative. E=hf is quantitative because it has h

How does the wave model of electrons orbiting the nucleus account for the fact that the electrons can have only discrete energy values?

through the formation of standing waves that close on themselves constructively

to remove glare from a polished floor, should polaroid axis be vertical or horizontal?

vertical

how does the direction of polarization compare to the direction of vibration of the electron produced?

vertical vibration produces vertical polarization

for which color, yellow or green, will the distance between the fringes be greater?

yellow has longer wavelengths than green

does the photoelectric effect prove light is made of particles? do interference experiments prove light is composed of waves?

yes, it proves these

in what way does light from distant stars tell astronomers that atoms throughout the universe have the same properties of those on earth?

you can see the same emission and absorption lines in stars everywhere