light and atoms Flashcards
what creates an electromagnetic wave
the oscillation of an electron
roughly show the visible light spectrum and the colors associated with there frequency
draw the wave diagram of a vertical and horizontally positioned antenna with axis labels
what is the definition of monochromatic light
mono chromatic light is light composed of a single frequency
what is a coherent wave source
a coherent wave source is a wave source that is in phase and has the same frequency
why is white light neither monochromatic or coherent
because white light is made up of lots of different colors of light it isn’t monochromatic and these are out of phase therefore not coherent
what is required to have a good observable diffraction effect
the wavelength must be similar to the slit size
what is required to have a good observable diffraction effect
the wavelength must be similar to the slit size
what is diffraction
diffraction is the bending of a wave as it passes through an opening or around an obstacle
what does an intensity distribution of a diffraction grating glook like
what formula would you use to find the maximum orders for a diffraction grating
what is the photoelectric effect
the photoelectric effect is the emission of electrons when illuminated by light of high enough frequency
what effect does increasing the intensity but not the frequency have on the readings
there is a higher current detected
what effect does increasing the frequency have on the readings
when the frequency is increased the kinetic energy is increased
how did Einstein explain the photo electric effect
draw a graph of ek max vs frequency label and explain all the intercepts and the slope and what happens if a metal with a higher threshold frequency is measured
the slope would be equal to planks constant
how does an x-ray differ from a standard photoelectric effect
-they have a continuous range of frequency’s
-an x-ray is caused by accelerating an electron not a photon
-there are high intensity peaks at certain frequencies
why does an x-ray have a continuous range of frequency’s
when an electron collides closer to the nucleus there is more energy as the path is changed by the electrostatic forces and the closer to the nucleus the more energy
draw a graph and explain what happens to a intensity vs frequency graph for an x-ray when the current is increased, the voltage is increased or the target metal is changed
what is attenuation
attenuation is the reduction in x-rays as they pass through a material due to the absorption or scattering of x-ray photons
what can effect attenuation
-the thicker a material is the greater the attenuation
-the denser the material the less x-rays can pass through
-the greater the atomic number of a material the greater the attenuation
what is the diffrence between hard and soft x-rays
a hard x-ray is used when doing things like chest or leg x-rays and have high photon energies and frequency’s
soft x-rays are used on things with low attenuation and will have relatively low photon energies and frequency’s
what was de Broglie’s proposal
de Broglie proposed that moving particles have a wavelength that depends on there momentum
what is the formula for de Broglie’s wave length
lambda= h/p
how can line emission spectra be produced
by heating to high temperatures or placing a large potential diffrence through it
how does the minimum work for a material relate to the different states
the eV diffrence from n=1 to n=infinity is equal to the minimum work required to release an electron
what is the diffrence between a photon exiting an electron and another electron exciting an electron
when a photon excites an electron the energy level in the photon must be exactly equal to that of the diffrence between the state of the electron and another exited state. when an electron excites an electron it doesn’t have to be exact and as long as the energy of the incident electron is greater the diffrence it can transfer the energy and what ever is left pver is scattered
what is the diffrence between a photon exiting an electron and another electron exciting an electron
when a photon excites an electron the energy level in the photon must be exactly equal to that of the diffrence between the state of the electron and another exited state.
when an electron excites an electron it doesn’t have to be exact and as long as the energy of the incident electron is greater the diffrence it can transfer the energy and what ever is left over is scattered
how does the energy of the incident electron cause the peaks of an x-ray
when an incident electron of high enough energy collides with an electron in the ground shell it can knock it out of the atom. an electron from the next shell drops down causing an x-ray photon equal to the energy diffrence. this jump is often the pne with the largest potential diffrence therfore it causes the peaks
what is the ground states also referred to as
K-shell
what is n=2 also referred to as
L-shell
what is n=3 also referred to as
M-shell
explain the presence of absorption lines in the suns spectrum
the suns core creates a white light with a continuous range of frequencies. as the light passes through the atmosphere the temperature drops electrons within the cooler gasses then get exited by the suns photons and absorb them. removing them from the incident light
what is fluorescence
fluorescence is the when an electron that is exited releases more than one photon as it reverts to ground state
what is the diffrence between stimulated and spontaneous emission
spontaneous emission is when an electron is exited by a photon into a higher energy state and instantly returns to that state releasing one photon.
stimulated emission is when an electron in an exited state returns to a lower state because it is hit by an incident photon of the exact diffrence between the two states. this causes two photons to be emitted
what is metastable state and population inversion
metastable is when an electron stays in an exited state longer than expected. population inversion is when there are more atoms in an exited state than a ground state
what are the four fundamental forces
-electromagnetic
-weak nuclear
-strong nuclear
-gravitational
what is a gauge boson and what are the four Gauge bosons with corresponding forces
electromagnetic - photon
weak nuclear - W, Z
Strong nuclear - gluon
gravitational - graviton
describe the electromagnetic forces in terms of gauge bosons
a photon has an energy of E=hf. a photon emitted by one electron will cause a recoil. The closer the electron are the more energy they have.
describe the weak nuclear forces in terms of gauge bosons
when neutrinos interact they they are mediated by exchange bosons of W and Z.
describe the strong nuclear forces in terms of gauge bosons
the exchange of pions is what mediates the strong repulsive force between two protons. the exchange of pions between nucleons mediates the repulsive force.
what is an anti particle
an anti particle has the same mass, spin and lifespan of the particle but a their charge has opposite signs
what happens when an anti particle and a particle collide
they annihilat and release two photons in opposite directions. the energy released is in accordance with E=mc^2
