Electromagnetic Radiation And Quantum Phenomena Flashcards
How do you create the photo electric effect?
Shine light with a high enough frequency onto the surface of a metal, the metal will emit electrons.
What conclusions can be made from the photoelectric effect?
- if the frequency was below a certain value no photoelectrons were emitted, this value is the frequency threshold.
- Each electron has a kinetic energy, as the frequency increases past the threshold frequency, the kinetic energy gets greater.
- The number of photoelectrons is proportional of the intensity of the radiation.
Why can’t the photoelectric effect be proved by wave theory?
The higher the intensity of the wave the more energy should be transferred to each electron, the kinetic energy.
There also wouldn’t be a threshold frequency, eventually the electrons should be emitted no matter the frequency.
How is the photoelectric effect explained by light theory?
There is a one to one interaction between a photon ( packet of light ), and an electron on the metals surface, this means that there can only be an electron emitted if the frequency threshold is met.
What is the work function?
The minimum amount of energy required for electrons to be emitted from the surface of a metal.
What is the stopping potential?
The potential difference needed to be applied across a metal to stop the photoelectrons with the maximum kinetic energy.
What is the photoelectric equation?
E = hf = Φ + ½ Ekmax
What is the equation for stopping potential?
Ek = e x Vs where e is charge of an electron and Vs is the stopping potential in Volts.
How does increasing the intensity of a light effect the photoelectrons
More photoelectrons per second are produced
What is excitation?
When an electron gains energy through collisions with free electrons and Goes up an energy level,
What is ionisation?
When an electron gains enough energy to be removed from the atom completely, this occurs when the energy of the electron is greater than the ionisation energy.
How do excited electrons return to their original energy level?
By releasing the energy in the form of a photon.
Where is a good use of exciting and relaxing electrons?
Florescent tubes
