Photoelectric Effect Flashcards
What does the light cause?
Photo-emission of photoelectrons
How does light travel?
As a wave
How does light transfer its energy?
As a particle. A beam of light carries discrete particles called photons. The photons of the light have a characteristic energy determined by the frequency of the light
Every colour of light has a different….
Frequency
The ….. of photons of different colours of light will be different
Energy
Define threshold frequency
The minimum frequency of incident radiation at which electrons will be emitted from a particular metal
Define work function
The minimum amount of energy required to emit an electron from the surface of a metal
The number of electrons ejected per second from a metal increases with….
The intensity of the incident radiation (provided the frequency of the light is above threshold frequency)
If the frequency of the light is increased (more energy per photon)…..
The kinetic energy of the ejected electrons increases
An increase in the intensity of the light will….
Increase the number of electrons ejected per second (more photons arrive at the metal per second)
What is the significance of the photoelectric effect?
It established the quantum theory and the particle nature of light
What is used to measure charge?
Electroscope
What effect does a change in frequency have OK the number of electrons emitted per second?
No effect
What effect does the intensity of the light have on the number of electrons emitted per second?
More electrons will be emitted
What effect does the intensity of the light have on the kinetic energy of electrons?
No effect
What effect does the frequency have in the kinetic energy of the electrons?
A higher frequency means more kinetic energy (since the work function is constant).
hf - hfo = Ek
Why does intensity affect the number of electrons emitted in the way in which it does?
The more intense the light, the more photons arriving at the metal, and therefore the more electrons emitted per second. Therefore there is greater electrical current.
Define resistance
The ratio of potential difference to the current flowing across the ends of the conductor
Define photoelectric effect
The process that occurs when light shines in a metal and electrons are ejected.
