Grade 12 Physical Sciences · Matter and Materials · Paper 2 (Chemistry)

Photoelectric Effect Grade 12

Real Photoelectric Effect past paper questions and answers from 2023 to 2025, with each memo split into the ticks examiners give. Try one, mark yourself, and see exactly which skill cost you marks.

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Question 1.10 · November 2025 · Paper 1 · National (DBE) · 2 marks

Various options are provided as possible answers to the following questions. Each question has only ONE correct answer. Choose the answer and write only the letter (A–D) next to the question numbers (1.1 to 1.10) in the ANSWER BOOK, e.g. 1.11 E.

1.10 Light of different wavelengths is incident on a metal surface.

Which ONE of the following graphs shows the CORRECT relationship between the maximum kinetic energy of the photoelectrons,

E_{k (ma x)}

, and the inverse of the wavelength of the incident light,

\frac{1}{λ}

?(2)

A Graph A
B Graph B
C Graph C
D Graph D

Work it out on paper first. Then mark yourself with the official memo, one tick at a time.

Photoelectric Effect skills

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More Photoelectric Effect Grade 12 questions and answers

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4. Question 4.2.1 · November 2025 · Paper 1 · National (DBE) · 3 marks
Cricketers at an academy conduct an experiment to determine the relationship between the contact time and the final momentum of a ball for a constant average net force.

A cricket ball of mass $150$ g is thrown horizontally with a certain initial velocity and is struck by a bat so that the ball moves in the opposite direction, as shown in the diagram below. The average net force acting on the ball is horizontal.

The experiment is repeated using the same ball. The average net force and the initial velocity of the ball are kept constant. The contact time between the bat and the ball is changed EACH time. The results obtained are shown in the sketch graph below.
4.2 Calculate the:
4.2.1 Average net force acting on the ball(3)
Show the memo (3 ticks)Memo
1. ✓
  METHOD 1: Change in final momentum (numerator)Gradient $= F_{n e t} = \frac{Δ p _{f}}{Δ ( Δ t )}$
  $= \frac{4 , 5 - 0}{\dots}$
  1 mark · Read a graph of results
2. ✓
  METHOD 1: Change in contact time (denominator) $F_{n e t} = \frac{4 , 5 - 0}{0 , 03 - 0 , 01} = 225$ N
  1 mark · Read a graph of results
3. ✓
  METHOD 1: Answer with direction $F_{n e t} = 225$ N to the right / opposite to the original direction of the ball
  1 mark · Read a graph of results
5. Question 1.10 · November 2024 · Paper 1 · National (DBE) · 2 marks
1.10 Which of the following statements is/are TRUE for the photoelectric effect?

The photoelectric effect demonstrates that:

(i) Light has a wave nature
(ii) Light has a particle nature
(iii) Light energy is quantised(2)
1. A (i) only
2. B (ii) only
3. C (i) and (iii) only
4. D (ii) and (iii) only
Show the memo (1 tick)Memo
1. ✓
  Correct optionIn the photoelectric effect each electron is ejected by ONE photon, a packet (quantum) of energy $E = h f$ . Electrons are ejected only above the threshold frequency, however intense the light. This shows the particle nature of light (ii) and that light energy is quantised (iii). The wave model cannot explain it, so (i) is not demonstrated.
  
  B is the trap: it misses that the photon idea also means the energy comes in quanta.
  
  Answer: D
  2 marks · Explain the photoelectric effect
6. Question 10.1 · November 2024 · Paper 1 · National (DBE) · 2 marks
10.1 Define the term photoelectric effect.(2)
Show the memo (1 tick)Memo
1. ✓
  Definition of the photoelectric effectThe process whereby electrons are ejected from a metal surface when light (of suitable frequency) is incident/shining on that surface.
  2 marks · Define photoelectric effect terms
7. Question 1.10 · May/June 2024 · Paper 1 · National (DBE) · 2 marks
Various options are provided as possible answers to the following questions. Each question has only ONE correct answer. Choose the answer and write only the letter (A–D) next to the question numbers (1.1 to 1.10).
1.10 Which ONE of the following combinations is CORRECT for a line absorption spectrum in terms of the ENERGY TRANSITIONS OF THE ATOMS and the APPEARANCE OF THE NARROW LINES IN THE SPECTRUM?(2)
1. A Energy transition of the atoms: Higher to lower energy state; Appearance of the narrow lines: Dark lines
2. B Energy transition of the atoms: Lower to higher energy state; Appearance of the narrow lines: Coloured lines
3. C Energy transition of the atoms: Lower to higher energy state; Appearance of the narrow lines: Dark lines
4. D Energy transition of the atoms: Higher to lower energy state; Appearance of the narrow lines: Coloured lines
Show the memo (1 tick)Memo
1. ✓
  Choose the correct optionIn an absorption spectrum, atoms absorb photons of particular energies, so electrons move from a LOWER to a HIGHER energy level. Those frequencies are missing from the continuous spectrum, so they show as DARK lines.
  
  Answer: C
  2 marks · Explain emission and absorption spectra
8. Question 10.1 · May/June 2024 · Paper 1 · National (DBE) · 2 marks
10.1 Define the term photoelectric effect.(2)
Show the memo (1 tick)Memo
1. ✓
  Definition of the photoelectric effectThe process whereby electrons are ejected from a (metal) surface when light of suitable frequency is incident on that surface.
  2 marks · Define photoelectric effect terms
9. Question 8.2 · May/June 2024 · Paper 2 · National (DBE) · 2 marks
The relationship between the concentration of the electrolyte and the cell potential is investigated using the following electrochemical cell represented by the cell notation:

Aℓ(s) | $A ℓ^{3 +}$ (aq) || $M^{2 +}$ (aq) | M(s)

The concentration of $M^{2 +}$ is changed and the corresponding emf is measured. The concentration of $A ℓ^{3 +}$ (aq) and the temperature are at standard conditions. The graph below shows the results of this investigation.
8.2 Determine the concentration of $M^{2 +}$ (aq) that will produce an emf of $1, 87$ V.(2)
Show the memo (1 tick)Memo
1. ✓
  Value read from the graph $0, 325$ (mol·dm $^{- 3}$ )
  2 marks · Read a graph of results
10. Question 1.10 · November 2023 · Paper 1 · National (DBE) · 2 marks
Various options are provided as possible answers to the following questions. Each question has only ONE correct answer.
1.10 Light of a suitable frequency is shone on the surface of a metal and electrons are ejected from the metal.

Which ONE of the following is equal to the ratio of the work function to the threshold frequency of the metal?(2)
1. A Planck's constant
2. B The inverse of Planck's constant
3. C The energy of the incident photons
4. D The maximum kinetic energy of the ejected electrons
Show the memo (1 tick)Memo
1. ✓
  Correct option $W_{0} = h f_{0}$ , so $\frac{W _{0}}{f _{0}} = h$ , Planck's constant.
  
  Answer: A
  2 marks · Use the photoelectric equation

Photoelectric Effect Grade 12 videos

Short lessons from South African teachers first. Videos load only when you tap play, to save your data.

Electromagnetic radiation calculations Grade 10 PhysicsMiss Martins Maths and Science

Threshold Frequency and Work Function Grade 12 Photoelectric EffectMiss Martins Maths and Science

The Photoelectric Equation Grade 12 Photoelectric Effect PhysicsMiss Martins Maths and Science

Photoelectric Effect grade 12: Introduction and OverviewMiss Martins Maths and Science

Emission & Absorption Spectra Explained | Grade 12 Physical SciencesDanike Aucamp_Wiskunde en Wetenskap

Metric Unit Prefix Conversions: How to Convert Metric System Prefixes | Crash Chemistry AcademyCrash Chemistry Academy

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