/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 63 Through what angle must a \(200 ... [FREE SOLUTION] | 91Ó°ÊÓ

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Through what angle must a \(200 \mathrm{keV}\) photon be scattered by a free electron so that the photon loses \(10 \%\) of its energy?

Short Answer

Expert verified
The photon must be scattered by approximately \(38.94°\).

Step by step solution

01

Understand the Problem

We are tasked with finding the scattering angle of a photon after colliding with a free electron, given that it loses 10% of its energy. The photon's initial energy is \(200 \mathrm{keV}\), and thus the post-collision energy will be \(180 \mathrm{keV}\).
02

Identify Relevant Formula

We will use the Compton scattering formula: \[\lambda' - \lambda = \frac{h}{m_e c} (1-\cos \theta)\]where \(\lambda'\) is the final wavelength, \(\lambda\) is the initial wavelength, \(h\) is Planck's constant, \(m_e\) is the electron mass, \(c\) is the speed of light, and \(\theta\) is the scattering angle. We will first calculate the initial and final wavelengths.
03

Calculate Initial and Final Wavelength

The energy of a photon is given by \(E = \frac{h c}{\lambda}\). Rearranging gives \(\lambda = \frac{h c}{E}\). For the initial energy: \(\lambda = \frac{h c}{200 \times 10^3 eV}\).For the final energy: \(\lambda' = \frac{h c}{180 \times 10^3 eV}\).Calculate \(\lambda\) and \(\lambda'\) using these expressions with \(h = 4.135667696 \times 10^{-15} \, eV\cdot s\) and \(c \approx 3 \times 10^8 \, m/s\).
04

Compute Change in Wavelength

Find the difference \(\Delta \lambda = \lambda' - \lambda\) to use in the Compton formula. Substitute \(\lambda'\) and \(\lambda\) calculated in the previous step.
05

Solve for the Scattering Angle \(\theta\)

Substitute \(\Delta \lambda\) into the Compton formula to solve for \(\theta\):\[\Delta \lambda = \frac{h}{m_e c} (1 - \cos \theta)\]Use \(\Delta \lambda\) and constants \(h = 6.62607015 \times 10^{-34} J\cdot s\), \(m_e = 9.10938356 \times 10^{-31} kg\), and \(c = 3 \times 10^8 m/s\) to find \(\theta\).
06

Calculate \(\theta\) Using \(\cos^{-1}\)

Isolate \(\cos \theta\) from the equation \[1 - \cos \theta = \frac{\Delta \lambda \cdot m_e c}{h}\]Then solve for \(\theta = \cos^{-1}(1 - \frac{\Delta \lambda \cdot m_e c}{h})\). Calculate the angle in degrees.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Photon Energy Loss
In the process of Compton scattering, an incoming photon collides with a stationary or free electron, resulting in a reduction in the photon's energy. This energy loss can be quantified through the percentage decrease in the photon's initial energy. For example, in the given problem, a photon with an initial energy of 200 keV loses 10% of its total energy after the collision.
This energy loss leads the photon to have reduced energy, namely 180 keV, after the collision. Understanding energy loss is crucial because it determines the subsequent behavior of the photon, including changes in its wavelength and the scattering angle. Significantly, photon energy loss highlights one of the fundamental aspects of the interaction between light and matter. It showcases how energy conservation plays a crucial role when photons and electrons interact. This concept is essential for understanding the scattering and absorption phenomena observed in various physical systems.
Scattering Angle Calculation
To find out how much a photon scatters during Compton scattering, we calculate the scattering angle, which indicates the deflection of the photon after collision with an electron. The scattering angle, denoted by \( \theta \), can show us how the direction of the photon changes due to energy transfer during the collision.In solving the original exercise, we are tasked with determining this angle when a photon loses a part of its energy. By applying the Compton equation \( \lambda' - \lambda = \frac{h}{m_e c} (1 - \cos \theta) \), where \( \lambda \) and \( \lambda' \) are the initial and final wavelengths respectively, we can solve \( \theta \).
This requires calculating the change in wavelength, \( \Delta \lambda \), due to energy loss, and how it relates to the angle of deflection using cosine functions. Understanding this allows for insights into the extent of deviation a photon undergoes upon colliding with an electron, integral for scientific experiments analyzing photon behavior and electron interactions.
Wavelength Change
In this context, wavelength change is a direct consequence of energy transfer during the Compton scattering interaction. Photons alter their wavelength when they transfer energy to electrons. The key relationship is given by the equation:\[\Delta \lambda = \lambda' - \lambda = \frac{h}{m_e c} (1 - \cos \theta)\]Where:
  • \(\lambda'\) is the post-collision wavelength, and \(\lambda\) is the initial wavelength.
  • \(h\) represents Planck's constant.
  • \(m_e\) is the electron's mass.
  • \(c\) stands for the speed of light.
A change in wavelength, \( \Delta \lambda \), occurs because the photon's wavelength is inversely proportional to its energy. When the photon loses energy, the corresponding increase in wavelength is observed. This is why in Compton scattering, a higher energy loss results in a more significant wavelength change.
Understanding wavelength change is vital for interpreting results in experiments like X-ray scattering, and medical imaging techniques, where photon-electron interactions are analyzed extensively.
Planck's Constant
Planck's constant, often denoted as \( h \), plays a quintessential role in quantifying phenomena in quantum mechanics. It relates the energy of photons to their wavelength and frequency, serving as a bridge between the particle and wave characteristics of light.In the context of the Compton scattering formula, Planck's constant determines the proportionality factor between the change in the photon's wavelength and the scattering angle. The typical value used in calculations is \( h = 6.62607015 \times 10^{-34} \text{J}\cdot\text{s} \) or can be expressed in terms of \( \text{eV}\cdot\text{s} \) for photon measurements.Significantly, Planck's constant is not just a pillar in equations, but also frames our understanding of quantized energy exchanges, including light-matter interactions like those studied in Compton scattering. It emphasizes the dual nature of electromagnetic waves and is foundational in the evolution of quantum theory, enhancing insights into the photon's behavior across various scientific fields.

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Most popular questions from this chapter

Electrons accelerated to an energy of \(60 \mathrm{GeV}\) have a de Broglie wavelength \(\lambda\) small enough for them to probe the structure within a target nucleus by scattering from the structure. Assume that the energy is so large that the extreme relativistic relation \(p=E / c\) between momentum magnitude \(p\) and energy \(E\) applies. (In this extreme situation, the kinetic energy of an electron is much greater than its rest energy-) (a) What is \(\lambda\) ? (b) If the target nucleus has radius \(R=5.0 \mathrm{fm}\), what is the ratio \(R / \lambda\) ?

A light detector (your eye) has an area of \(2.00 \times 10^{-6} \mathrm{~m}^{2}\) and absorbs \(80 \%\) of the incident light, which is at wavelength \(500 \mathrm{~nm}\). The detector faces an isotropic source, \(3.00 \mathrm{~m}\) from the source. If the detector absorbs photons at the rate of exactly \(4.000 \mathrm{~s}^{-1}\), at what power does the emitter emit light?

Singly charged sodium ions are accelerated through a potential difference of \(300 \mathrm{~V}\). (a) What is the momentum acquired by such an ion? (b) What is its de Broglie wavelength?

What is the wavelength of (a) a photon with energy \(1.00 \mathrm{eV}\), (b) an electron with energy \(1.00 \mathrm{eV}\), (c) a photon of energy \(1.00 \mathrm{GeV}\), and \((\mathrm{d})\) an electron with energy \(1.00 \mathrm{GeV} ?\)

What are (a) the energy of a photon corresponding to wavelength \(1.00 \mathrm{~nm}\), (b) the kinetic energy of an electron with de Broglie wavelength \(1.00 \mathrm{~nm}\), (c) the energy of a photon corresponding to wavelength \(1.00 \mathrm{fm}\), and (d) the kinetic energy of an electron with de Broglie wavelength \(1.00 \mathrm{fm}\) ?

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