more photoelectric effect and wave-particle duality

what equation did Einstein make about conservation of energy in photons?

• hf = work function + maximum kinetic energy

• the energy of each individual photon must be conserved because all its energy is transferred to the photoelectron

why do some electrons require more energy than others?

• electrons are different distances away from the surface of the metal and some are closer to the positive ions than others

• an electron which requires the minimum energy to free it would have the maximum kinetic energy

what does the graph of kinetic energy vs incident frequency?

• kinetic energy= hf - work function

• the y intercept is the negative work function

• the gradient is planck’s constant

what is wave-particle duality?

• the idea that subatomic particles have wavelengths and can be made to exhibit wave properties like diffraction

• also electromagnetic radiation can be described as waves (just normal waves) or particles (photons)

• normally applied to electrons, but also works for neutrons and protons too (they’re just harder to observe due to their large mass/ large momentum, small wavelength)

what is electron diffraction?

• if an electron gun fires electrons at a thin piece of polycrystalline graphite, the electrons pass between the individual carbon atoms

• the gap between the atoms is similar in size to the wavelength of the electrons

• so the electrons form a diffraction pattern

• the electrons behave as particles when they are accelerated by the high p.d, then as waves when they diffract, then as particles when they hit the screen with discrete impacts

what is the de broglie equation?

• wavelength = h / momentum

• therefore wavelength is inversely proportional to the momentum as planck’s constant is a constant lol

what’s another equation?

• wavelength= h / square root of (2*kinetic energy*mass)

• derived from kinetic energy equation and momentum