What is meant by work function (2) Minimum energy required by an electron to escape from (1) a metal surface (1)
Minimum energy required to remove an electron from an atom (1) from the ground
What is meant by ionisation energy? (2)
state (1)
Energy of a photon is fixed/constant (1)
Why do emitted electrons have a kinetic Energy is required for electrons to overcome work function ø (1)
energy that varies up to a maximum value? Electrons deeper into/below the surface of the metal require more energy to
(4) overcome work function and therefore have less KE(1)
Maximum KE = Energy of photon - work function ø (1)
Explain how (bright ring) diagram is Diffraction pattern maxima/minima (bright and dark areas) (1)
evidence of the wave-particle duality of Diffraction is a property of waves- proves wave-behaviour of electrons (1)
electrons?
What is meant by the ground state? The lowest energy state of an atom
An electron receives a discrete amount of energy for BOTH (1)
Explain the difference between excitation
Excitation promotes an electron to a higher energy level
and ionisation (2)
Ionisation is when an electron receives enough energy to leave the atom
discrete energy levels (1)
Electrons need to absorb a DISCRETE amount of energy to move to a higher energy
Explain why only photons of certain
level (1)
frequencies cause excitation (4)
Photons need to have a certain frequency to provide this energy, because E=hf (1)
interaction is a 1:1 reaction all of the photon's energy is absorbed (1)
Electrons flow through the tube to the applied PD causing a current to flow (1)
Explain how excitation takes place in a
Electrons collide with mercury atoms in the tube (1)
fluorescent tube
This raises electrons in the mercury atom to a higher energy level (1)
UV/ High energy photons emitted from mercury atoms when the electrons in the atom
What is the purpose of coating in a de-excite (1)
fluorescent tube? High energy photons absorbed by the coating (1)
Coating emits photons in the visible spectrum (1)
particle and an anti-particle collide and cease to exist (1)
What happens when annihilation occurs? (2)
Their mass is released as energy in the form of a pair of gamma photons (1)
aqa a level physics paper 1
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