CURRICULUM FET
PHYSICAL SCIENCES
TUTOR MATERIAL
SPRING SCHOOL 2025
BACK ON TRACK PROGRAMME
GRADE 12
,TOPIC: PHOTOELECTRIC EFFECT
DATE: October 2025
Examination Guidelines 2021
Photo-electric effect
• Describe the photoelectric effect as the process whereby electrons are ejected
from a metal surface when light of suitable frequency is incident on that surface.
• State the significance of the photoelectric effect.
• Define threshold frequency, fo, as the minimum frequency of light needed to emit
electrons from a certain metal surface.
• Define work function, Wo, as the minimum energy that an electron in the metal
needs to be emitted from the metal surface.
• Perform calculations using the photoelectric equation:
E =Wo+ Ek(max), where E = hf and Wo= hfo and Ek(max) = ½ mv2max
• Explain the effect of intensity and frequency on the photoelectric effect.
• State that the photoelectric effect demonstrates the particle nature of light.
Emission and absorption spectra
• Explain the formation of atomic spectra by referring to energy transition.
• Explain the difference between atomic absorption and emission spectra.
o An atomic absorption spectrum is formed when certain frequencies of
electromagnetic radiation passing through a substance is absorbed.
For example, when light passes through a cold gas, atoms in the gas
absorb characteristic frequencies of the light and the spectrum
observed is a continuous spectrum with dark lines where
characteristic frequencies of light were removed. The frequencies of
the absorption lines are unique to the type of atoms in the gas.
o An atomic emission spectrum is formed when certain frequencies of
electromagnetic radiation are emitted due to an atom making a
transition from a higher energy state to a lower energy state.
For example, atoms in a hot gas emit light at characteristic
frequencies. The spectrum observed is a line spectrum with only a few
coloured lines of frequencies unique to the type of atom that is
producing the emission lines.
Grade 12 Tutoring Programme: Physical Sciences 2
, PRE-TEST TOTAL: 6 Marks
• You will be given 10 minutes to do the Pre-test after which it will be marked by your
tutor.
• Once the Pre-test has been marked by your tutor, you may then continue with the
long questions that follow.
PRE-TEST: PHOTOELECTRIC EFFECT NAME: _________________
QUESTION 1 (MULTIPLE-CHOICE)
1.1 The following graph shows the relationship between the maximum (2)
kinetic energy, EK(MAX), of photoelectrons and the frequency, f, of the
incident electromagnetic wave.
What physical unit is represented by point X (the vertical intercept)
on the graph?
Maximum kinetic energy of photoelectron (J)
Frequency (Hz)
X
A Planck's constant
B The work function of the metal.
C The threshold frequency of the metal.
D The threshold wavelength of the metal.
Grade 12 Tutoring Programme: Physical Sciences 3
PHYSICAL SCIENCES
TUTOR MATERIAL
SPRING SCHOOL 2025
BACK ON TRACK PROGRAMME
GRADE 12
,TOPIC: PHOTOELECTRIC EFFECT
DATE: October 2025
Examination Guidelines 2021
Photo-electric effect
• Describe the photoelectric effect as the process whereby electrons are ejected
from a metal surface when light of suitable frequency is incident on that surface.
• State the significance of the photoelectric effect.
• Define threshold frequency, fo, as the minimum frequency of light needed to emit
electrons from a certain metal surface.
• Define work function, Wo, as the minimum energy that an electron in the metal
needs to be emitted from the metal surface.
• Perform calculations using the photoelectric equation:
E =Wo+ Ek(max), where E = hf and Wo= hfo and Ek(max) = ½ mv2max
• Explain the effect of intensity and frequency on the photoelectric effect.
• State that the photoelectric effect demonstrates the particle nature of light.
Emission and absorption spectra
• Explain the formation of atomic spectra by referring to energy transition.
• Explain the difference between atomic absorption and emission spectra.
o An atomic absorption spectrum is formed when certain frequencies of
electromagnetic radiation passing through a substance is absorbed.
For example, when light passes through a cold gas, atoms in the gas
absorb characteristic frequencies of the light and the spectrum
observed is a continuous spectrum with dark lines where
characteristic frequencies of light were removed. The frequencies of
the absorption lines are unique to the type of atoms in the gas.
o An atomic emission spectrum is formed when certain frequencies of
electromagnetic radiation are emitted due to an atom making a
transition from a higher energy state to a lower energy state.
For example, atoms in a hot gas emit light at characteristic
frequencies. The spectrum observed is a line spectrum with only a few
coloured lines of frequencies unique to the type of atom that is
producing the emission lines.
Grade 12 Tutoring Programme: Physical Sciences 2
, PRE-TEST TOTAL: 6 Marks
• You will be given 10 minutes to do the Pre-test after which it will be marked by your
tutor.
• Once the Pre-test has been marked by your tutor, you may then continue with the
long questions that follow.
PRE-TEST: PHOTOELECTRIC EFFECT NAME: _________________
QUESTION 1 (MULTIPLE-CHOICE)
1.1 The following graph shows the relationship between the maximum (2)
kinetic energy, EK(MAX), of photoelectrons and the frequency, f, of the
incident electromagnetic wave.
What physical unit is represented by point X (the vertical intercept)
on the graph?
Maximum kinetic energy of photoelectron (J)
Frequency (Hz)
X
A Planck's constant
B The work function of the metal.
C The threshold frequency of the metal.
D The threshold wavelength of the metal.
Grade 12 Tutoring Programme: Physical Sciences 3
