Photoeletric Effect Flashcards
What is the main evidence for the particle like behaviour of light?
The photoelectric effect
What are photons?
Discrete packets of light
How to you find the Energy of a photon?
E = hf
What is the value of planks constant?
6.63 x 10^-34
What happens if you shine UV light onto a surface?
Depending on its frequency electrons could be liberated from the surface.
What is the evidence that disproves the wave like effect of light?
The photoelectric effect,
This is because if light acted just like a wave then we would see electrons being liberated at any frequency given that it was bright enough. How ever this does not happen.
Explain the equipment setup to prove the photoeletric effect?
A battery is connected to an ammeter, which two metal plates are inside an evacuated tube. The battery is setup so that when electrons are liberated these electrons will face an opposite force form the battery.
How do you measure the kinetic Engel y of electrons in the photoelectric effect?
Turn up the V (potential difference) of the battery until no electrons reach the other plate.
- Ek = eV, this equation means times the potential difference needed to stop the electrons by their charge.
What is the threshold frequency?
The photoelectric effect only occurs if the frequency of the EM radiation is above a certain value.
What is time of emission related to the photoelectric effect?
It is the fact that electron sarny either emitted or not emitted as soon as they are exposed to the EM radiation. This means they can’t store energy.
What is the effect of intensity during the protectrices effect?
The more intense the light the more electrons are emitted because there are more photons to collide with more electrons.
What happens if you increase the frequency during the photoeletric effect?
If the frequency is above the threshold frequency then increasing the frequency will increase the speed of the electrons, which is the kinetic energy.
What is the work function in the photoeletric effect?
The work function is the energy required to liberate an electron from te surface.
- it can be calculated by:
Ek = hf - Φ
Or
f = Φ/h
