Define the term threshold frequency - NSC Physical Sciences - Question 10 - 2021 - Paper 1
Question 10
Define the term threshold frequency.
How does the maximum kinetic energy of photoelectrons emitted from cathode N compare to the maximum kinetic energy of those emi... show full transcript
Worked Solution & Example Answer:Define the term threshold frequency - NSC Physical Sciences - Question 10 - 2021 - Paper 1
Step 1
Define the term threshold frequency.
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Answer
The threshold frequency is defined as the minimum frequency of light needed to eject electrons from a metal surface. It represents the lowest frequency at which photoelectric emission occurs.
Step 2
How does the maximum kinetic energy of photoelectrons emitted from cathode N compare to the maximum kinetic energy of those emitted from cathode M?
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Answer
The maximum kinetic energy of photoelectrons emitted from cathode N is GREATER THAN that emitted from cathode M given that the light frequency exceeds the threshold frequency of both cathodes.
Step 3
Calculate the value of frequency fx indicated on the graph.
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Answer
From the graph, we see that the frequency corresponding to the y-intercept is given by fx=6.63×1034 Hz.
Step 4
The experiment is now repeated for cathode M using light of frequency fx, but of higher intensity.
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Answer
From the y-intercept of the graph: NO EFFECT.
The number of photoelectrons emitted per unit time: INCREASES.
The maximum kinetic energy of the emitted photoelectrons: NO EFFECT.
