Physics: Quantum Theory

blackbody

an ideal body or surface that completely absorbs all radiant energy that strikes it with no reflection and radiates at all frequencies with a spectral energy distribution dependent on its temperature

a black body is a what?

a perfect radiator and absorber of energy

blackbody radiation

energy given off by a blackbody

as temperature increases, the total energy given off the body

increases

examples of black bodies

sun and a hot stove burner are common examples of black bodies.

energy can be _____ light or in the directions of ______ or ______

visible, infrared, ultraviolet

violet light wavelength

400-440nm

blue light wavelength

440-480nm

green light wavelength

480-530nm

yellow light wavelength

530-590nm

orange light wavelength

590-630nm

red light wavelength

630-700nm

radiation below 400nm is referred to as _______ and radiation above 700nm is called _____ radiation

ultraviolet, infrared

ultraviolet catastrophe

the failed prediction of classical physics that the energy radiated by a blackbody at ultraviolet wavelengths is extremely large and that the total energy radiated is infinite

based on classical physics the equations ____ work for ultraviolet frequencies

did not

predictions of wave theory suggested that the intensity of the light should ______ as the wavelength ______

increase, decreased

at low wavelengths (high frequencies), the intensity should become _____, meaning limitless and impossible to measure or calculate

infinite

instead, experimental data kept producing a _____ in these ____ frequency ranges

peak, high

who resolved the issue by proposing that electromagnetic energy did not follow classical physics?

max planck

light energy could only be carried in ____ packets of energy proportional to the frequency

discrete

the variable n represents the ____ _____.

quantum number

energy is

quantized

quantized packets of lights are called

photons

an example of quantized energy can be seen in electron behavior, electrons will “____” between quantum states or energy levels based on the energy ____ or ______

jump, absorbed, released

where in nature can this concept be seen?

aurora borealis, northern lights

light energy is an _______ wave

electromagnetic

this means that a light wave has both an oscillating ______ and _____ field

magnetic, electric

electromagnetic waves radiate _____ in all directions from the source

outward

all electromagnetic waves are considered ___ ____.

light waves

electromagnetic waves vary and are organized based on their ______ and ______

frequency, wavelength

an ____ _____ is defined as the energy that an electron or proton ____ when it is accelerated through a potential difference of 1volt

electron volt, gains

in 1873, ____ _____ discovered that light was a form of ________ waves

James Maxwell, electromagnetic

Maxwell’s theories were supported by Heinrich Hertz however, later experiments conducted by Hertz could not be explained by what?

the wave model of the nature of light

photoelectric effect

the emission of electrons from a metal surface that occurs when light of certain frequencies shines on the surface of the metal

the electrons emitted are called

photoelectrons

in agreement with classical physics, light waves have ____, this ____ can pull electrons from their atoms and _____ the metal.

energy, escape

None of the predictions were observed experimentally, instead no electrons were emitted below a certain frequency, regardless of _____.

intensity

this was called

threshold frequency

if the frequency exceeds the threshold frequency, the photoelectric effect is ______

observed

the number of photoelectrons emitted is _____ to the light intensity but the maximum kinetic energy of the photoelectrons is ______ of the light intensity

proportional, independent

photoelectron maximum kinetic energy ______ with increasing frequency

increases

electrons are emitted almost ______

instantaneously

______ resolved the conflict in a 1905 paper on the photoelectric effect where he received a nobel prize in 1921

einstein

he extended the plancks concept of _______ to electromagnetic waves

quantization

einstein suggested that a stream of particles (_____) has an ______, E

photons, energy

in his theory each electron is ______ as a unit of energy by an electron

absorbed

the smallest amount of energy an electron must have to escape the surface of a metal is called the _____ _____, W

work function

threshold frequency depends on the ____ ____ of the surface

work function

energy is conserved and there is a _____/direct relationship between frequency and maximum kinetic energy

linear

photon theory

explains features of the photoelectric effect that cannot be explained or understood using classical physics concepts.

each photons has

momentum, energy

each photon travels at the

speed of light

the compton shift supports einstein’s theories about

photons

compton shift

the photoelectric effect is observed when x rays or gamma rays are scattered on a material with an increase in wavelength

when a photon collides with an electron initially at rest, some of the photons energy and momentum would transfer to the electron resulting in a longer _____

wavelength