---
title: "In three separate Compton scattering trials, an incident photon collides with an electron that is initially stationary and free to move.  Case 1: A photon of wavelength \\(\\lambda_0\\) scatters through an angle of \\(\\theta = 90^\\circ\\).  Case 2: A photon of wavelength \\(\\lambda_0\\) scatters through an angle of \\(\\theta = 180^\\circ\\).  Case 3: A photon of wavelength \\(2\\lambda_0\\) scatters through an angle of \\(\\theta = 180^\\circ\\).  Which of the following correctly ranks the kinetic energy \\(K_e\\) gained by the electron in each case?"
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url: "https://nerd-notes.com/ubq/123556/"
date_modified: "2026-09-28T12:00:09+00:00"
---

# In three separate Compton scattering trials, an incident photon collides with an electron that is initially stationary and free to move.

Case 1: A photon of wavelength \(\lambda_0\) scatters through an angle of \(\theta = 90^\circ\).

Case 2: A photon of wavelength \(\lambda_0\) scatters through an angle of \(\theta = 180^\circ\).

Case 3: A photon of wavelength \(2\lambda_0\) scatters through an angle of \(\theta = 180^\circ\).

Which of the following correctly ranks the kinetic energy \(K_e\) gained by the electron in each case?

In three separate Compton scattering trials, an incident photon collides with an electron that is initially stationary and free to move.

Case 1: A photon of wavelength \(\lambda_0\) scatters through an angle of \(\theta = 90^\circ\).

Case 2: A photon of wavelength \(\lambda_0\) scatters through an angle of \(\theta = 180^\circ\).

Case 3: A photon of wavelength \(2\lambda_0\) scatters through an angle of \(\theta = 180^\circ\).

Which of the following correctly ranks the kinetic energy \(K_e\) gained by the electron in each case?

![A 2D schematic on a plain background showing a Compton collision. At the center sits a small filled circle labeled e^-. From the left, an incoming wavy arrow labeled \lambda points horizontally toward the electron. A horizontal dashed reference line extends to the right from the electron. A second wavy arrow representing the scattered photon extends from the electron upward and to the right at an angle labeled \theta relative to the horizontal dashed line. A straight solid arrow representing the recoiling electron extends from the electron downward and to the right. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790596809-r4GyrK.jpg)

- **A.** \(K_{e,2} > K_{e,3} > K_{e,1}\)
- **B.** \(K_{e,2} > K_{e,1} = K_{e,3}\)
- **C.** \(K_{e,2} > K_{e,1} > K_{e,3}\)
- **D.** \(K_{e,3} > K_{e,2} > K_{e,1}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123556/*