Potential Well Flashcards
What is the Work Function (∅)?
The MINIMUM energy required for an electron to escape the surface of a metal.
Electrons further down the potential well require a higher work function
What is the threshold energy?
The energy at which the electron has escaped the surface of the metal, but is unable to move as it has no KE. (hf = ∅)
What is the Threshold Frequency?
The frequency at which you reach the threshold energy.
What is the equation for the energy of a photon, including the work function and kinetic energy?
hf = ∅ + KE
What is the photoelectric effect?
When photons give electrons on the surface of a material enough energy to escape the surface of that material
Why is light released when electrons get excited then de - excite?
Because when they de - excite they release energy in the form of visible light, the magnitude of which is dependent on the size of the level it fell to.
Why do electrons de-excite?
Because when they get excited, they become unstable, and must de-excite to become stable again.
What wavelengths of light will eject more electrons with more kinetic energy, higher or lower?
Lower, as the wavelength is indirectly proportional to the frequency, making hf bigger when ℷ is lower, resulting in more KE
How does the gold leaf experiment display the photoelectric effect?
It displays incoming photons exciting the electrons off the surface of the metal, which then causes the now postively charged metal to repel the postively charged leaf.
Which colour of light has the lowest energy?
Red
Which colour of light has the lowest wavelength?
Blue
On a graph of kinetic energy against frequency, what does the gradient display and what do the x and y intercepts show?
Plancks constant is shown by the gradient
The x intercept shows the threshold frequency
The y intercept shows the **MAGNITUDE **of the work function
