PHYSICS FINAL CH 30
Ch30 homework #5 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?
They are proportional they are equal
Ch 30 homework #39 What is the evidence for the claim that iron exists in the relative cool outer layer of the sun?
When a spectrum of the Sun is compared with the spectrum of the element iron, the iron lines overlap and perfectly match certain Fraunhofer lines. This is evidence for the presence of iron in the Sun.
Ch30 homework #48 How can a hydrogen atom, which has only one electron, have so many spectral lines?
Yes, if there is at least one intermediate energy state that the electron can transition to along the way. Though a hydrogen atom has only one electron, it contains a large number of shells, so when this single electron jumps from one shell to another, a photon is emitted, and the energy difference of the shells causes different wavelengths to be released...hence, mono-electronic hydrogen has many spectral lines.
Ch30 homework #11 What is a spectroscope, and what does it accomplish?
a device that measures the frequencies of light in a beam of light device to see the emission spectrum that is used to see beams of light
CH30 incandescent light depends on temperature because it is
a form of thermal radiation
CH30 electrons dropping to a lower energy level emit with each jump
a throbbing pulse of electromagnetic radiation called a photon
CH30 each component color is focused at definite positions
according to its frequency and forms an image of the slit on the screen.
CH30 the sun and stars are surrounded by
an atmosphere of cooler gasses that absorb some of the light coming from the main body because of this discovered helium
Ch30 homework #7 Which has the higher frequency: red or blue light? Which has the greater energy per photon; red or blue light?
blue and blue have higher frequency and energy per photon
CH30 the temperature can be determined
by measuring the peak frequency ( or color) of the radiant energy they emit
CH30 Just as each electrically neutral element has its own number of electrons, each element has its own
characteristic set of energy levels
CH30 absorption spectrum
dark lines distributed through out; these dark lines against a rainbow-colored background are like emission lines in reverse. they are absorption lines
Ch30 CheckPoint Distinguish among emission spectra, continuous spectra, and absorption spectra.
emission spectra are produced by thin gasses in which atoms do not experience many collisions. Continuous spectra result when atoms continuously colide, which is why solids, liquids, and dense gases emit light at all visible frequencies when heated. absorption spectra occur when light passes though a dilute gas and atoms in the gas absorb at characteristic frequencies. Because the re-emitted light is unlikely to be emitted in the same direct as the absorbed photons, dark lines(absence of light) appear in the spectrum.
CH 30 every element has its own characteristic pattern of electron energy levels and therefore
emits light with its own characteristic pattern of frequencies which is its EMISSION SPECTRUM
CH30 Fire
every element, excited in flame or otherwise, emits its own characteristic color or colors.
CH30 when an electron is any way raised to a higher energy level the atom is said to be
excited
Ch30 homework #32 Green light is emitted when electrons in a substance make a particular energy-transition. If blue light were instead emitted from the same substance, would it correspond to a greater or lesser change of energy in the atom?
greater energy change
Ch30 homework #12 When a gas glows, discrete colors are emitted. When a solid glows, the colors are smudged. Why?
has to do with how many atoms are near by and how close they are to each other
CH30 When we view white light from an incandescent source we see a continuous spectrum of the rainbow
if a gas is placed between it shows that it is not quite continuous
CH30 the light emitted by atoms far from one another in the gaseous please is quite different from the light emitted by the same atoms closely packed in the solid phase
in gas atoms are far apart in solids they are closely packed - and outer electrons make transitions with neighboring atoms resulting in an infinite variety of transitions
Ch30 homework #6 How is the energy of a photon related to its vibrational frequency?
it is directly proportional
CH30 the electron is continuously undergoing acceleration in any orbit whether or not it changes energy levels
it should continuously radiate energy but it doesn't
CH 30 incandescence
light that is produces as a result of high temperature
CH30 this higher position is only momentary bc
like a spring on a door pulled open it soon returns to its original form
CH30 as the solid heats further
more high energy transitions occur and higher frequency radiation is emitted.
CH30 Does this mean that an infinite number of energy levels characterizes the tungsten atoms that make up the filament of the incandescent lamp?
no bc it would produce a blue color
CH30 we think of a photon as a
particle of light
CH30 the different color images of the slit are called
spectral lines
CH30 We can determine the speed of stars by
studying the spectra they emit
CH30 what sets incandescent light apart from the light of a neon tube or mercury vapor lamp is
that it contains an infinite number of frequencies, spread smoothly across the spectrum.
Ch 30 Check point From the radiation curves, which emits the higher average frequency of radiant energy: the 1000 C source or the 1500 C source? Which emits the most radiant energy?
the 1500C radiating source emits the higher average frequency the 1500C source is a brighter and also emits more radiant energy, as noted by the greater vertical line.
CH30 de-excitation
the atom looses its temporarily acquired energy when the electron returns to a lower level and emits radiant energy
CH30 atoms absorb light as well as emit light
the atoms of the gas absorb light of selected frequencies from the beam
CH30 neon lights
the different colors in the signs correspond to the excitation of different gases. electrons are boiled off these electrode and jostled back and forth at high speeds by a high ac voltage they smash into millions of target atoms, boosting orbital electrons into higher energy levels The overall result of this process is the transformation of ELECTRIC ENERGY into RADIANT ENERGY
CH30 a photon's frequency is related to
the energy transition of the jump E=hf
CH30 a moving light source produces a shift in its light frequency
the frequency (not speed!!) of light emitted by an approaching source is higher, while the frequency of a receding source is lower, than the frequency of a stationary source the corresponding spectral lines go toward red almost all galaxies show a red shift in their spectra, evidence the universe is expanding
CH30 light emitted by each element in the vapor phase produces its now characteristic pattern of lines
the lines correspond to the electron transitions between atomic energy levels fingerprints
CH30 An electron from the nucleus has a greater electric potential energy with respect to the nucleus that does an electron closer to the nucleus
the more distant electron is in a higher energy state or at a higher energy level
Ch30 Check Point Suppose a friend suggests that, for the first rate operation, the gaseous neon atoms in a neon tube should be periodically replaced with fresh atoms because the energy of the atoms tend to be used up with continued excitation, producing dimmer and dimmer light. What do you say to this?
the neon atoms don't release any energy that is not given to them by the electric current. Any single atoms may be excited and re-excited without limit. If the light is becoming dimmer and dimmer it is probably because there is a leak a fresh atom is indistinguishable from a used one both are ageless
CH30 if a temperature of an object is doubled
the peak frequency of emitted radiation is doubled
Ch30 homework #34 If we double the frequency of light, we double the energy of each of its photons. If we instead double the wavelength of light what happens to the photon energy?
the photon energy decreases
CH30 the frequencies that were absorbed appear as dark lines
the positions of the lines correspond exactly to the positions of lines in an emission spectrum of the same gas
CH30 the curve compromises a continuous spectrum
the predominant frequency of emitted radiation, the peak frequency, is directly proportional to the absolute temperate of the emitter f=t
Ch30 Check Point Spectral patterns are not shapeless smears of blue light but, instead, consist of fine and distinct straight lines. Why is this so?
the spectral lines are simply images of the slit
Ch30 homework #75 How does the surface temperature of reddish, bluish, and whitish stars compare?
the temp is lowest for red medium for white and hottest as blue
Ch30 homework #14 How does an absorption spectrum differ in appearance from an emission spectrum?
there are dark lines distributed throughout it; these dark lines against a rainbow-colored background are like emission lines in reverse. They are absorption lines.
CH30 the Sun is an incandescent light but the spectrum is not continous
there are many absorption lines called Fraunhofer lines similar lines are found in the spectra produced by stars
CH30 emission spectrum
this pattern can be seen when light is passed though a prism onto a viewing screen behind which is a SPECTROSCOPE
CH30 it is customary to refer to colors in terms of their
wavelengths rather than their frequencies
Ch30 homework #72 Since every object has some temperature, every object radiates energy. Why, then, can't we see objects in the dark?
we cant see them in the dark as they do not emit energy. the reason we see them in light is because light doesn't go through them. it hits it, and reflects off
Ch30 homework #29 The energy difference between states A and B is twice the energy difference between states B and C. In a transition(quantum jump) from C to B, and electron emits a photon of wavelength 600nm. what is the wavelength emitted when the photon jumps from B to A? when it jumps from C to A
300 200 twice as great as frequency twice as small as wavelength
Ch30 homework #76
?????
Ch 30 homework #45 Does atomic excitation occur in solids as well as in gasses? How does the radiant energy from an incandescent solid differ from the radiant energy emitted by an excited gas?
Atomic excitation occurs in solids, liquids, and gasses. Because atoms in a solid are closely packed, radiation from them( and liquids) is smeared into a broad distribution to produce a continuous spectrum, whereas radiation from widely spaced atoms in a gas is in separate bunches that produce discrete "lines" when diffracted by a grating.
Ch 30 homework #4 In a neon tube, what occurs immediately after an atom is excited?
It drops to a lower energy level