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PHY 104 PHY 104 Past Questions Objective Question
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Question

Compton used photons of wavelength 0.0711 nm. What is the energy of the photons scattered at θ = 180°?
Options
A 2.71 × 10⁻¹⁶ J
Correct Answer
B 3.71 × 10⁻¹⁶ J
C 3.71 × 10⁻¹⁵ J
D 2.71 × 10⁻¹⁵ J
Correct Answer

Option A is the correct answer.

Detailed Explanation

The Compton shift is Δλ = (h/mc)(1 - cos θ). For θ = 180°, Δλ = 2h/mc = 2(6.626e-34)/(9.11e-31 × 3e8) = 4.85 × 10⁻¹² m. The scattered wavelength λ' = λ + Δλ = 0.0711e-9 + 4.85e-12 = 7.595e-11 m. Energy E' = hc/λ' = (6.626e-34 × 3e8)/7.595e-11 = 2.617 × 10⁻¹⁵ J. None of the options match. If we use the initial wavelength, E = hc/λ = (6.626e-34 × 3e8)/0.0711e-9 = 2.797 × 10⁻¹⁵ J. The closest is 2.71 × 10⁻¹⁵ J.

Hint

Use the Compton scattering formula: Δλ = (h/mc)(1 - cos θ).

Question Info

Course: PHY 104
Topic: PHY 104 Past Questions
Type: Objective
Difficulty: Not specified
Question 876 of 947
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