Introduction to Radiation Physics

Introduction to Radiation Physics

• Radiation physics studies ionizing and non-ionizing radiation, and their interactions with matter.
• X-rays were discovered by Roentgen in 1895.
• A basic knowledge of atomic physics is essential to understand x-ray production and interactions.

Composition of Matter

• Matter occupies space and has weight.
• An atom is the fundamental unit of matter, and it cannot be subdivided.

Bohr Model

• The Bohr model, introduced by Neil Bohr in 1983, describes atomic structure.
• An atom has a small, positively charged nucleus (containing protons and neutrons).
• Electrons orbit the nucleus in specific energy levels.
• These electron orbits are fixed and correspond to particular energy levels.

Quantized Energy Levels

• Electrons can only occupy specific energy levels (shells or orbitals).
• Electrons may move from one level to another by absorbing or emitting specific amounts of energy.

Electrostatic Forces

• Electrostatic forces hold electrons in their orbits by attracting them to the positively charged nucleus.

Emission and Absorption of Energy

• Electrons transitioning between energy levels emit or absorb energy in the form of electromagnetic radiation.

Structure of an Atom

• Atoms consist of three primary subatomic particles: protons, neutrons, and electrons.
• Protons are positively charged and found in the nucleus.
• Neutrons are neutral (no charge) and found in the nucleus.
• Electrons are negatively charged and orbit the nucleus in shells.
• The number of protons determines the element.
• A stable atom has an equal number of protons and electrons.

Atomic Number and Mass Number

• Atomic Number (Z): The number of protons in an atom's nucleus.
• Mass Number (A): The sum of protons and neutrons in the nucleus.
• A stable atom's proton number equals the electron number.

Electrostatic and Centrifugal Forces

• Electrostatic force (Coulomb's law): The fundamental force of attraction between electrically charged objects.
• Centrifugal force: The apparent outward force on an object moving in a circular path.
• To maintain stable electron orbits, the attractive electrostatic force must balance the centrifugal force pushing the electron outward.

Binding Energy

• Binding energy is the energy required to hold the nucleus together.
• The energy released when nucleons form a nucleus keeps the nucleus stable.

Radiation Physics

• It is a branch of physics relating to the interactions of ionizing and non-ionizing radiation with matter.
• Ionizing and non-ionizing radiation are different based on the energy levels associated with the processes.

Ionizing Radiation

• Definition: Ionizing radiation has enough energy to remove electrons from atoms forming ions.
• Examples : X-rays, gamma rays, alpha particles, beta particles, and certain high-energy subatomic particles (like neutrons).
• Properties: ionising radiation has high energy and can penetrate matter deeply, causing potential damage to biological tissues and DNA.
• Applications: Medical imaging (X-rays, CT scans), radiation therapy, industrial radiography, nuclear physics research.

Non-Ionizing Radiation

• Definition: Non-ionizing radiation does not have enough energy to ionize atoms or molecules.
• Examples: Radio waves, microwaves, infrared radiation, visible light, and ultraviolet (UV) radiation.
• Properties: It has lower energy and generally doesn't penetrate matter as deeply as ionizing radiation.
• Applications: Radio and television, microwave ovens, cell phones, Wi-Fi, and laser devices.

This quiz explores key concepts in radiation physics, including ionizing and non-ionizing radiation, atomic structure, and the Bohr model. It is essential for students to grasp how matter interacts with radiation to understand x-ray production. Challenge yourself with these core principles essential for studying physics.