Which graph shows the variation of momentum $p$ with wavelength $\lambda$ of a photon?
A
B
C
D - AQA - A-Level Physics - Question 13 - 2020 - Paper 1
Question 13
Which graph shows the variation of momentum $p$ with wavelength $\lambda$ of a photon?
A
B
C
D
Worked Solution & Example Answer:Which graph shows the variation of momentum $p$ with wavelength $\lambda$ of a photon?
A
B
C
D - AQA - A-Level Physics - Question 13 - 2020 - Paper 1
Step 1
Identify the relationship between momentum and wavelength
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Answer
The momentum p of a photon is inversely proportional to its wavelength λ. This relationship is given by the formula:
p=λh
where h is Planck's constant. From this equation, as the wavelength increases, the momentum decreases.
Step 2
Analyze the graph options
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Answer
Given the inverse relationship, the correct graph should show a curve that decreases as λ increases. This indicates that for larger wavelengths, the momentum is lower.
Step 3
Select the correct graph
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Answer
Based on the analysis, the correct answer is option C, which shows a decreasing trend as λ increases, consistent with the relation p=λh.