Glossary
Backscattering
A specific case of scattering where the scattered particle (e.g., photon) reverses its direction, resulting in the maximum possible change in wavelength.
Example:
When a photon undergoes backscattering (a 180° scattering angle), it transfers the maximum possible energy to the electron.
Compton Scattering
A phenomenon where a photon collides with a charged particle, typically an electron, resulting in a decrease in the photon's energy (increase in wavelength) and a change in its direction.
Example:
When an X-ray photon interacts with an electron in a material, it undergoes Compton Scattering, losing some energy and deflecting from its original path.
Compton Scattering Equation
A formula that quantifies the change in wavelength of a photon after Compton scattering, relating it to Planck's constant, electron mass, speed of light, and the scattering angle.
Example:
Using the Compton Scattering Equation, scientists can precisely predict the wavelength shift of X-rays after they interact with electrons in a material.
Conservation Laws
Fundamental principles in physics stating that certain quantities, such as energy and momentum, remain constant in a closed system before and after an interaction.
Example:
The conservation laws of energy and momentum are essential for analyzing collisions in physics, from car crashes to subatomic particle interactions.
Electrons
Fundamental subatomic particles with a negative electric charge, often involved in interactions with photons.
Example:
In a cathode ray tube, a beam of electrons is accelerated to create an image on the screen.
Energy and Momentum Transfer
The process by which energy and momentum are exchanged between interacting particles, such as a photon and an electron during a collision.
Example:
During a game of pool, the cue ball's energy and momentum transfer to the object ball, causing it to move.
Frequency
The number of complete wave cycles that pass a point per unit of time, inversely related to wavelength for electromagnetic waves.
Example:
As a photon's wavelength increases due to Compton scattering, its frequency decreases, indicating a loss of energy.
Mass of the Electron (m_e)
The intrinsic mass of an electron, a constant value used in calculations involving electron interactions.
Example:
The mass of the electron is a crucial value in the denominator of the Compton scattering equation, influencing the magnitude of the wavelength shift.
Particle-like Behavior
The characteristic of light (or other waves) to exhibit properties typically associated with particles, such as discrete energy packets and momentum.
Example:
The photoelectric effect and Compton scattering are key experiments demonstrating the particle-like behavior of light.
Photons
Discrete packets or quanta of light energy, demonstrating the particle-like nature of light.
Example:
A laser pointer emits millions of photons every second, each carrying a specific amount of energy.
Planck's Constant (h)
A fundamental physical constant that relates the energy of a photon to its frequency, central to quantum mechanics.
Example:
The energy of a single photon of blue light can be calculated by multiplying its frequency by Planck's Constant.
Scattering Angle
The angle at which a scattered particle (e.g., a photon) deviates from its original direction after a collision.
Example:
A larger scattering angle in Compton scattering indicates that the photon transferred more energy to the electron.
Speed of Light (c)
The constant speed at which all electromagnetic waves, including light, travel in a vacuum.
Example:
The speed of light is the ultimate speed limit in the universe, approximately 3 x 10^8 meters per second.
Wavelength Change (Δλ)
The difference between the initial and final wavelengths of a photon after undergoing Compton scattering.
Example:
A positive wavelength change indicates that the scattered photon has a longer wavelength and thus less energy than the incident photon.