Q7 · 2020 · Paper 2Simple familiar3 marks
QUESTION 7 (3 marks)
A photoelectric effect experiment is conducted by shining different frequencies of light on a sample of aluminium. The kinetic energy of the ejected photoelectrons was measured. The data is plotted in the graph.
Identify the mathematical relationship between kinetic energy, , and incident frequency, .
WORKED SOLUTION
3 marksQCAA guide · typeset solution
ANSWER
See worked solution below.
Worked solution
Gradient =
∆𝐸𝐸𝐾𝐾
∆𝑓𝑓=
5.6×10−19−1.5×10−21
1.25×1015−4.68×1014 = 7.2 × 10−34
Work function = y-intercept = 3.3 × 10−19J
𝐸𝐸𝐾𝐾= 7.2 × 10−34 × 𝑓𝑓−3.3 × 10−19
• provides a correct value for the y-intercept
[1 mark]
• provides a correct value for the gradient of the
graph [1 mark]
• provides the equation [1 mark]
One QCAA sample method typeset for web; criterion wording is adapted from the official marking guide.
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