7-Quantum Behaviour Flashcards
By modelling light as a wave, what three things can you explaing?
Refraction, diffraction and inteference
What are photons?
Quanta of light
When the picture is bright, is the chance of photons arriving high or low?
The chance is high
When the picture is dim, is the chance of protons arriving high or low?
The chance is low
How can electromagnetic radiation be emitted?
In energy quanta
What is energy quanta?
Discrete packets of energy
What equation relates energy to Planck’s constant?
E = hf
What is the value of Planck’s constant?
6.6 X 10^-34
What are the units of Planck’s constant?
Js
As frequency = c / wavelength, what equation can be derived?
E = hc / wavelength
When discussing the energy of photons or subatomic particles, what energy unit do we use?
Electron volts
What is the magnitude of the charge on one electron?
1.6 X 10^19
What is charge measured in?
Coulombs C
What equation relates work done and voltage?
Work done = Voltage X Charge
What is the photoelectric effect?
The emission of electrons when light of sufficiently high frequency strikes a metal surface
What is the intensity of light?
The amount of energy transferred per metre squared per second
What did the wave model of light suggest about the photoelectric effect?
A more intense source of light would striking the metal would result in the emission of photoelectrons with greater kinetic energy
In the photelectric effect experiment, was the kinetic energy of the photons being ejected affected by the intensity of the light striking it?
No, a more intense light produced greater numbers of photoelectrons, but the maximum energy of the photons depends on the frequency of light
In the photoelectric effect experiment, what did the maximum energy of the photoelectrons depend on?
Only the frequency of light
In a photoelectric effect experiment, what happens if the frequency is below the threshold frequency?
No electrons are released no matter how bright the light source was
What does it take to remove an electron from a metal surface?
It takes energy
What is the work function?
The energy it takes to remove an electron from a metal’s surface
What does the maximum kinetic energy of a photoelectron equal?
hf - work function
When one photon strikes the surface of a metal, what happens?
It transfers energy hf to an individual electron. Some of the energy goes to releasing the electron from the surface of the metal and the remaining energy is transferred as the kinetic energy of the electron
What does the gradient of an energy against frequency graph for the maximum kinetic energy of photelectrons equal?
The Planck’s Constant, as H = E /f
How can electrons lose and gain energy?
By changing energy levels
When an electrons falls from a higher energy level, what do atoms do?
They release photons
When atoms release photons, what does the photon’s energy equal?
Energy equal to the difference between the levels
When a compound or element is heated, what dp the electrons in the atoms do?
They move into higher energy levels
When electrons fall back to lower energy levels, what are released?
Photons
Why are atoms able to emit light of different wavelenengths?
Atoms of each element have their own set of energy levels, meaning they emit photons of different energies-light of different wavelengths
