AQA A LEVEL PHYSICS PAPER 1 2025/2026
MARKING SCHEME (VERIFIED)
What |is |meant |by |work |function |(2) |- |ANS-Minimum |energy |required |by |an |electron |to |escape |from |
(1) |a |metal |surface |(1)
What |is |meant |by |ionisation |energy? |(2) |- |ANS-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) |- |ANS-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? |- |ANS-
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? |- |ANS-The |lowest |energy |state |of |an |atom
Explain |the |difference |between |excitation |and |ionisation |(2) |- |ANS-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) |- |ANS-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 |- |ANS-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? |- |ANS-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) |- |ANS-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) |- |ANS-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 |- |ANS-light |of |a |single |frequency
What |is |meant |by |coherent |- |ANS-constant |phase |difference
Effect |on |diffraction |pattern |when |wavelength |decreases |(3) |- |ANS-Maxima |closer |together |(1) |angle |
decreases |(1) |smaller |path |difference |(1)
MARKING SCHEME (VERIFIED)
What |is |meant |by |work |function |(2) |- |ANS-Minimum |energy |required |by |an |electron |to |escape |from |
(1) |a |metal |surface |(1)
What |is |meant |by |ionisation |energy? |(2) |- |ANS-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) |- |ANS-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? |- |ANS-
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? |- |ANS-The |lowest |energy |state |of |an |atom
Explain |the |difference |between |excitation |and |ionisation |(2) |- |ANS-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) |- |ANS-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 |- |ANS-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? |- |ANS-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) |- |ANS-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) |- |ANS-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 |- |ANS-light |of |a |single |frequency
What |is |meant |by |coherent |- |ANS-constant |phase |difference
Effect |on |diffraction |pattern |when |wavelength |decreases |(3) |- |ANS-Maxima |closer |together |(1) |angle |
decreases |(1) |smaller |path |difference |(1)
