aqa a level physics paper 1 Questions &
Answers
What is meant by work function (2) - ANSWER-Minimum energy required by an electron to escape from
(1) a metal surface (1)
What is meant by ionisation energy? (2) - ANSWER-Minimum energy required to remove an electron
from an atom (1) from the ground state (1)
Why do emitted electrons have a kinetic energy that varies up to a maximum value? (4) - ANSWER-
Energy of a photon is fixed/constant (1)
Energy is required for electrons to overcome work function ø (1)
Electrons deeper into/below the surface of the metal require more energy to overcome work function
and therefore have less KE(1)
Maximum KE = Energy of photon - work function ø (1)
Explain how (bright ring) diagram is evidence of the wave-particle duality of electrons? - ANSWER-
Diffraction pattern maxima/minima (bright and dark areas) (1)
Diffraction is a property of waves- proves wave-behaviour of electrons (1)
What is meant by the ground state? - ANSWER-The lowest energy state of an atom
Explain the difference between excitation and ionisation (2) - ANSWER-An electron receives a discrete
amount of energy for BOTH (1)
Excitation promotes an electron to a higher energy level
Ionisation is when an electron receives enough energy to leave the atom
Explain why only photons of certain frequencies cause excitation (4) - ANSWER-discrete energy levels (1)
, Electrons need to absorb a DISCRETE amount of energy to move to a higher energy level (1)
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)
Explain how excitation takes place in a fluorescent tube - ANSWER-Electrons flow through the tube to
the applied PD causing a current to flow (1)
Electrons collide with mercury atoms in the tube (1)
This raises electrons in the mercury atom to a higher energy level (1)
What is the purpose of coating in a fluorescent tube? - ANSWER-UV/ High energy photons emitted from
mercury atoms when the electrons in the atom de-excite (1)
High energy photons absorbed by the coating (1)
Coating emits photons in the visible spectrum (1)
What happens when annihilation occurs? (2) - ANSWER-particle and an anti-particle collide and cease to
exist (1)
Their mass is released as energy in the form of a pair of gamma photons (1)
How does the strong nuclear force between two nucleons vary with the separation of the nucleons? (3) -
ANSWER-repulsive at < 0.5 fm (1)
attractive from 0.5 to 3 fm (1)
above 3 fm, force 0 (1)
What is meant by monochromatic light - ANSWER-light of a single frequency
What is meant by coherent - ANSWER-constant phase difference
Effect on diffraction pattern when wavelength decreases (3) - ANSWER-Maxima closer together (1) angle
decreases (1) smaller path difference (1)
Answers
What is meant by work function (2) - ANSWER-Minimum energy required by an electron to escape from
(1) a metal surface (1)
What is meant by ionisation energy? (2) - ANSWER-Minimum energy required to remove an electron
from an atom (1) from the ground state (1)
Why do emitted electrons have a kinetic energy that varies up to a maximum value? (4) - ANSWER-
Energy of a photon is fixed/constant (1)
Energy is required for electrons to overcome work function ø (1)
Electrons deeper into/below the surface of the metal require more energy to overcome work function
and therefore have less KE(1)
Maximum KE = Energy of photon - work function ø (1)
Explain how (bright ring) diagram is evidence of the wave-particle duality of electrons? - ANSWER-
Diffraction pattern maxima/minima (bright and dark areas) (1)
Diffraction is a property of waves- proves wave-behaviour of electrons (1)
What is meant by the ground state? - ANSWER-The lowest energy state of an atom
Explain the difference between excitation and ionisation (2) - ANSWER-An electron receives a discrete
amount of energy for BOTH (1)
Excitation promotes an electron to a higher energy level
Ionisation is when an electron receives enough energy to leave the atom
Explain why only photons of certain frequencies cause excitation (4) - ANSWER-discrete energy levels (1)
, Electrons need to absorb a DISCRETE amount of energy to move to a higher energy level (1)
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)
Explain how excitation takes place in a fluorescent tube - ANSWER-Electrons flow through the tube to
the applied PD causing a current to flow (1)
Electrons collide with mercury atoms in the tube (1)
This raises electrons in the mercury atom to a higher energy level (1)
What is the purpose of coating in a fluorescent tube? - ANSWER-UV/ High energy photons emitted from
mercury atoms when the electrons in the atom de-excite (1)
High energy photons absorbed by the coating (1)
Coating emits photons in the visible spectrum (1)
What happens when annihilation occurs? (2) - ANSWER-particle and an anti-particle collide and cease to
exist (1)
Their mass is released as energy in the form of a pair of gamma photons (1)
How does the strong nuclear force between two nucleons vary with the separation of the nucleons? (3) -
ANSWER-repulsive at < 0.5 fm (1)
attractive from 0.5 to 3 fm (1)
above 3 fm, force 0 (1)
What is meant by monochromatic light - ANSWER-light of a single frequency
What is meant by coherent - ANSWER-constant phase difference
Effect on diffraction pattern when wavelength decreases (3) - ANSWER-Maxima closer together (1) angle
decreases (1) smaller path difference (1)
