7 - Quantization Flashcards
What is the photoelectric effect?
Photoelectric effect = the emission of electrons when light strikes a surface.
How is a current created?
When light is incident on the cathode it can cause electrons to break free.
They are then forced towards the anode, creating a current.
What does the work function determine?
Whether or not an electron will be released from a metal
What is the work function?
Work function = the minimum amount of energy required to free an electron from a metal.
What happens if more energy than the work function is given to an electron?
then it will have some additional kinetic energy when it breaks free
Do all electrons have the same kinetic energy?
Not all electrons have the same kinetic energy when they break free, some have more and some have less.
How can the maximum kinetic energy be measured?
by adjusting the battery in the circuit until the stopping potential is reached.
What is stopping potential
Stopping potential = the minimum potential difference required to stop the current in a photoelectric circuit.
What does the stopping potential represent?
The stopping potential represents setting the battery to just the right strength so that the fastest electrons are repelled away from the anode, thereby stopping the current.
Why do no free electrons appear unless the frequency of the light is greater than a minimum value, called the threshold frequency?
If the frequency of the light source is above the threshold frequency, each photon carries enough energy to overcome the work function.
Why does the stopping potential increase as the frequency of light increases?
The greater the frequency, the more energy delivered by each photon, and the greater the stopping potential.
Why does increasing the intensity of the light causes the current to increase, but has no effect on the threshold frequency nor the stopping potential?
The greater the intensity, the greater the number of photons, thus the greater the number of free electrons, thus the greater the current.
What is the maximum kinetic energy?
The maximum kinetic energy of an electron is the energy delivered by a photon minus the work function
What happens when a matter particle (not a photon) collides with an atom?
When a particle collides it usually only gives a fraction of its energy to the orbital electron. Excited electrons quickly transition back to a lower energy level, causing the emission of a photon.
