Chapter 3 - Quantum phenomena Flashcards
What is the formula relating work function, frequency and the maximum kinetic energy
Ek=hf-phi
Define the term photoelectricity
Emissions of electrons from a metal surface when illuminated by a light greater than the threshold frequency
Define the term work function
The minimum amount of energy required for an electron to escape from the metal surface
What is the formula relating current and the number of photoelectrons emitted per second?
current=number of photoelectrons emitted per second * charge of an electron
How can you plot hf=phi+Ek on a graph?
rearrange to Ek=hf - phi
so y =mx+ c
Explain why the intensity of light doesn’t affect the maximum kinetic energy of a photoelectron given it exceeds the threshold frquency
Each individual electrons absorbs 1 photon
Define the term electron volt
the work required to move an electron through 1 p.d.
When an electron is hit with an incident electron but isn’t excited/ionised how much energy does the electron have?
The same amount
Define the term excitation energies
The energy values at which an atom absorbs energy
What is the ground state also known as?
n=1
When an electron de-excites what is the energy of the emitted photon
hf = E1-E2
What do raindrops and prisms split white light into?
A continuous spectrum
How can you produce a discrete spectrum?
Use a glowing gas as the light source
What does de-excitation release?
A photon
Define wave-particle duality of light
Light can behave like particles or waves
When does light behave like a wave?
Diffraction, refraction, reflection
When does light behave like a particle?
The photoelectric effect, excitation, ionisation
Explain why discrete light spectrums are unique to that element
The energy levels are unique to that element; photons emitted are a characteristic of the element
What is the formula relating wavelength and momentum/ mass and velocity? (Used for matter particles)
lambda = h/p = h/mv
What is the formula for de Broglie’s wavelength? (used for matter particles)
lambda = h/p = h/mv
Matter particles have a wave particle nature, what formula can you use to work out the wavelength?
de Broglie’s wavelength formula
