IB Physics HL E 2 2 Hl Threshold Frequency Questions
Apply HL threshold-frequency ideas to decide when photoemission occurs, comparing photon energy, work function, wavelength and intensity.
- Syllabus
- First assessment 2025
- Course
- Physics HL
- Level
- HL
Exam points
- explain that photoemission requires photon frequency at or above the threshold frequency because each photon must supply the work function
- predict the effect of changing wavelength, frequency, intensity or metal work function on whether electrons are emitted
- calculate threshold frequency or maximum wavelength and interpret maximum-kinetic-energy versus frequency graphs for different metals
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IB Physics HL E 2 2 Hl Threshold Frequency Questions question 1
This question is in two parts. Part 1 is about the oscillation of a mass. Part 2 is about the photoelectric effect.
Part 1 Oscillation of a mass
A mass of 0.80 kg rests on a frictionless surface and is connected to two identical springs both of which are fixed at their other ends. A force of 0.030 N is required to extend or compress each spring by 1.0 mm . When the mass is at rest in the centre of the arrangement, the springs are not extended.
Question (a)
(a)
Part 2 Photoelectric effect
A student carries out a photoelectric experiment in which radiation is incident on a metal surface in a vacuum.
Explain why photoelectrons are not emitted from the metal surface unless the frequency of incident light exceeds a minimum value.
[ 2 ]
Question (b)
(b)
A graph of the results of the experiment show how the maximum kinetic energy of the emitted photoelectrons varies with the frequency f of the incident radiation.
Use the graph to
[ 1 ]
Question (i)
(i)
identify the minimum value of the frequency for photoelectrons to be emitted.
[ 1 ]
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