Chapter 42: Problem 38
An X-ray beam with a wavelength of exactly \(5.00 \times 10^{-14} \mathrm{~m}\) strikes a proton that is at rest \(\left(m=1.67 \times 10^{-27} \mathrm{~kg}\right)\). If the X-rays are scattered through an angle of \(110^{\circ}\), what is the wavelength of the scattered X-rays?
Short Answer
Expert verified
The wavelength of the scattered X-rays is approximately \( 5.18 \times 10^{-14} \, \text{m} \).
Step by step solution
01
Identify and understand Compton's Equation
The problem discusses the scattering of X-rays, which is a typical situation for applying Compton's Effect. Compton's equation is given by \( \lambda' - \lambda = \frac{h}{m c} (1 - \cos \theta) \), where \( \lambda' \) is the wavelength after scattering, \( \lambda \) is the original wavelength, \( h \) is Planck's constant \((6.63 \times 10^{-34} \text{ Js})\), \( m \) is the mass of the proton, \( c \) is the speed of light \((3.00 \times 10^8 \text{ m/s})\), and \( \theta \) is the scattering angle. In this case, the angle \( \theta \) is \( 110^{\circ} \).
02
Convert angle to radians
Since trigonometric functions typically use radians, convert the angle from degrees to radians. The formula is \( \text{radians} = \frac{\pi}{180} \times \text{degrees} \). So, \( 110^{\circ} = \frac{\pi}{180} \times 110 \approx 1.91986 \text{ radians} \).
03
Calculate the change in wavelength using Compton's Equation
Plug the values into Compton's equation: \( \Delta \lambda = \frac{h}{m c} (1 - \cos(1.91986)) \). Calculate \( \cos(1.91986) \approx -0.342 \). Then, \( \Delta \lambda = \frac{6.63 \times 10^{-34}}{(1.67 \times 10^{-27})(3.00 \times 10^8)} \times (1 + 0.342) \).
04
Solve for the Change in Wavelength
Compute \( \Delta \lambda = \frac{6.63 \times 10^{-34}}{5.01 \times 10^{-19}} \times 1.342 \approx 1.77 \times 10^{-15} \text{ m} \). This is the increase in wavelength due to the scattering.
05
Find the new wavelength
Add the change in wavelength to the original wavelength: \( \lambda' = \lambda + \Delta \lambda = 5.00 \times 10^{-14} + 1.77 \times 10^{-15} \approx 5.18 \times 10^{-14} \text{ m} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
X-ray diffraction
X-ray diffraction is a fascinating phenomenon that occurs when X-rays encounter a material and are scattered in various directions. This process can reveal insightful information about the material's internal structure, particularly at the atomic or molecular level.
X-rays are a form of electromagnetic radiation with very short wavelengths, typically in the range of 0.01 to 10 nanometers. When these rays strike a material, they interact with the electrons within the atoms, causing the waves to scatter.
- The scattering pattern is unique to each substance, allowing scientists to use X-ray diffraction to study and identify the arrangement of atoms in a crystal.
- By analyzing these patterns, researchers can deduce the physical properties of materials.
Photon scattering
Photon scattering is a fundamental concept where photons, which are the basic units or quanta of light, interact with particles or matter and change direction. This process is crucial in a wide range of physical and scientific phenomena.
When a photon collides with a particle, such as an electron or a proton, it may be deflected or absorbed and then re-emitted. This interaction can lead to changes in the energy or direction of the photon.
- One famous type of photon scattering is the Compton Scattering, named after Arthur Compton, who first observed it in 1923.
- Compton Scattering specifically involves X-ray photons and their interactions with target particles, like electrons, to shift their wavelengths.
Wavelength shift
In the context of photon interactions, such as Compton Scattering, a wavelength shift indicates a change in the wavelength of a photon after it has collided with a particle. This shift is a form of energy transfer, reflecting changes in either momentum or energy between the interacting entities.The Compton Effect describes how the wavelength of X-rays increases after colliding with particles, like electrons, which was revolutionary in supporting the quantum theory of light. This shift provides vital evidence of the photon-electron interaction.
- Using the Compton Equation: \( \lambda' - \lambda = \frac{h}{m c} (1 - \cos \theta) \), we can calculate the change in wavelength, where \( \lambda' \) is the scattered wavelength.
- The equation shows that the shift depends on the angle of scattering \( \theta \) and the constants involved, linking physical properties to measurable outcomes.