Chapter 7 - Quantum Behaviour Flashcards
Describe photons.
Electromagnetic waves of frequency f are emitted and absorbed in quanta of energy E = hf, called photons.
What is energy quanta?
Discrete packets of energy.
What is the value of Planck constant? (2sf)
6.6 * 10^-34
What are the two equations for energy in this chapter?
E = hf = hc / lamda
What is an electron volt (eV)?
A measure of energy for atomic and nuclear physics, given by the kinetic energy acquired by an electron falling through a p.d. of 1 V. 1 eV = 1.6 *10^-19 J.
What is the photoelectric effect?
The emission of electrons when light of a sufficiently high enough frequency strikes a metal surface.
What is light intensity?
The amount of energy transferred per metre per second.
The maximum energy of ejected electrons depends only on…
frequency of the light.
The maximum energy of ejected electrons is not affected by…
the intensity of the light.
The brighter / more intense the light is, the greater…
number of photoelectrons ejected.
What happens if the light frequency is lower than the certain threshold frequency, f0?
No electrons will be released, no matter how bright the light source.
What is the work function of a metal?
The amount of energy required to remove an electron from its metal surface.
What is the equation for the maximum kinetic energy of the ejected electrons?
E = hf - “work function”
Threshold frequency * Planck constant =
Work function
