In a photoelectric investigation, light of different frequencies was radiated on each of two metals, A and B - NSC Physical Sciences - Question 10 - 2023 - Paper 1
Question 10
In a photoelectric investigation, light of different frequencies was radiated on each of two metals, A and B. The graph of maximum kinetic energy of the ejected elec... show full transcript
Worked Solution & Example Answer:In a photoelectric investigation, light of different frequencies was radiated on each of two metals, A and B - NSC Physical Sciences - Question 10 - 2023 - Paper 1
Step 1
10.1 Write down the numerical value of the gradient of the graph.
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Answer
The gradient of the graph, which represents the relationship between maximum kinetic energy and frequency, is calculated as:
extGradient=6.63×10−34 J s.
Step 2
10.2 Define the term work function.
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Answer
The work function, denoted as ( W_0 ), is the minimum energy required to eject electrons from the surface of a metal. It is mathematically expressed as:
W0=hf0
where ( h ) is Planck's constant and ( f_0 ) is the threshold frequency.
Step 3
10.3.1 Work function of metal A
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Answer
To calculate the work function of metal A, we use the formula:
W0=hf
Thus, for metal A, substituting the values:
W0=6.63×10−34 J s×12.54×1014 Hz=3.32×10−19 J.
Step 4
10.3.2 Value of X shown on the graph
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Answer
From the graph, the value of X, which is the maximum kinetic energy corresponding to the frequency of 12.54 x 10^14 Hz, is:
X=5×10−19 J.
Step 5
10.4 How will EACH of the following be affected if light of frequency 12,54 x 10^14 Hz, but of higher intensity, is used?
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10.4.1 The value of X:
No Effect: Increasing the intensity of the light does not affect the energy of individual photons, hence does not change the value of X.
10.4.2 The number of photoelectrons emitted per unit time:
Increases: A higher intensity means more photons, leading to more electrons emitted.
Step 6
10.5 Sketch the graph for metal B.
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Answer
To sketch the graph for metal B on the same axes as graph A, start by drawing a parallel line to graph A, but starting from a point lower on the energy axis, indicating a larger work function. Label this new line as graph B.
