TESTED AND CONFIRMED A+ ANSWERS
What is meant by work function (2) - Minimum energy required by an electron to escape
from (1) a metal surface (1)
What is meant by ionisation energy? (2) - Minimum energy required to r
...
TESTED AND CONFIRMED A+ ANSWERS
What is meant by work function (2) - Minimum energy required by an electron to escape
from (1) a metal surface (1)
What is meant by ionisation energy? (2) - 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)
- 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? -
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? - The lowest energy state of an atom
Explain the difference between excitation and ionisation (2) - 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) - 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 - 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? - 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)
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