Dictionary tag: A-B-C-D-E

• The electrostatic force is sometimes called the electric force. Both terms refer to the force that arises between charged particles. The word “electrostatic” emphasizes that the force is due to stationary (static) charges, while the word “electric” is a more general term that encompasses both static and moving charges.
• These two forces, electrostatic and magnetic articulate the behaviour of the electromagnetic field. They reveal that electric and magnetic fields are two facets of a unified electromagnetic field.
• The magnitude of the electrostatic force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
• The electrostatic force is the force between two electrically charged particles, regardless of whether they are moving or not.
• The magnetic force is the force between two moving electric charges, or between a magnetic field and a moving electric charge.
• The magnetic force is responsible for the attraction between oppositely charged magnets, such as a north pole and a south pole. It is also responsible for the repulsion between like-charged magnets, such as two north poles or two south poles.
• The magnetic force is responsible for the attraction between a magnet and a piece of iron. This is because iron is a ferromagnetic material, which means that it can be magnetized. When a magnet is brought near a piece of iron, the magnetic force of the magnet aligns the magnetic domains in the iron, causing the iron to become temporarily magnetized.
• The electrostatic force and the magnetic force are unified by Maxwell’s equations, which describe the behaviour of the electromagnetic field. Maxwell’s equations show that the electric and magnetic fields are two aspects of the same field and that they are related to each other.
• The electromagnetic force is one of the four fundamental forces of nature. The other three fundamental forces are the strong nuclear force, the weak nuclear force, and gravity. The electromagnetic force is the strongest of the four fundamental forces at the atomic and macroscopic levels.

• Elements are the building blocks of matter.
• Atoms are the particles that elements are composed of.
• Each element consists of a unique type of atom.
• Elements are represented by unique symbols, such as H for hydrogen and O for oxygen.
• Each type of atom has a different number of protons in its nucleus.
• The atomic number of an atom corresponds to the number of protons in its nucleus.
• The Periodic Table is a comprehensive inventory of elements, arranged according to their atomic numbers.
• The Periodic Table categorizes elements with similar properties and reveals trends and patterns in their chemical behaviour.
• Elements combine to form compounds with distinct characteristics and properties.

• A compound is a substance made from the combination of two or more elements and held together by chemical bonds that are difficult to break.
• Compounds have distinct properties that differ from those of their constituent elements.

• In the context of electromagnetism, there is only one elementary particle, the photon, which acts as the force carrier, transmitting the electromagnetic force and carrying energy and momentum.
• One way photons are created and destroyed is through subatomic processes within atoms and molecules.
• These processes often involve interactions between elementary particles governed by the strong nuclear force, which bind the building blocks of atoms (protons and neutrons) together.
• Remember that when photons are created within atoms and molecules through interactions like electron transitions and interactions with the strong nuclear force they produce light.
• Other light producing process (light sources) include: blackbody radiation (incandescent light bulb), nuclear fusion (sunlight), annihilation (gamma rays) and high-energy phenomena (supernovae).

Electromagnetic force

• The photon is the elementary particle associated with the electromagnetic force.
• It has no mass, no electric charge, and always travels at the speed of light in a vacuum.
• Photons carry electromagnetic energy and momentum.
• They are the building blocks of electromagnetic radiation, which encompasses a wide spectrum including light (visible and invisible), radio waves, X-rays, gamma rays, and more.

Strong Nuclear Force

• Gluons (g): These particles mediate the strong nuclear force, which binds quarks together to form protons and neutrons (collectively known as nucleons). Gluons themselves come in eight different “colours” and interact with each other, contributing to the strong force’s complex nature.

Weak Nuclear Force

• W and Z bosons (W⁺, W⁻, Z⁰): These three massive particles are responsible for mediating the weak nuclear force, which is involved in certain types of radioactive decay and some nuclear reactions. Unlike the photon and gluons, W and Z bosons have significant mass and participate in their own interactions.

Gravity (hypothetical)

• Graviton (G): While not yet directly observed, the graviton is the theorized force carrier for gravity. It is expected to be a massless particle with unique properties due to the nature of gravity itself. The search for the graviton is an active area of research in physics.

• Energy Changes in Atoms/Molecules: Atoms and molecules absorb and release energy, causing changes in electron positions or molecular vibrations. This energy is often emitted as electromagnetic radiation.
• Electron Transitions: Electrons jump between specific energy levels within an atom. When they absorb energy, they move to higher levels; when they return to lower levels, they release energy as photons.
• Molecular Vibrations: In molecules, atoms vibrate within chemical bonds. When energy is absorbed, these vibrations increase, and the energy can be emitted as electromagnetic radiation, often in the infrared spectrum.
• Atomic vibrations refer to the back-and-forth movements of individual atoms around their fixed positions. This is often discussed in solid-state physics, where atoms in a solid are arranged in a regular pattern and can oscillate slightly while remaining in place overall.

Types of Emission

• Electromagnetic radiation: The emission of photons, which are the energy packets of light and include electromagnetic waves like X-rays, gamma rays, radio waves, etc.
  • Electrons transition from higher to lower energy levels in atoms, emitting a photon with specific energy.
  • Radioactive nuclei decay, emitting high-energy photons like gamma rays.
• Particle emission: This involves the emission of subatomic particles themselves, such as electrons, neutrons, protons, or alpha particles.
  • Radioactive nuclei decay emits alpha particles or beta particles (electrons or positrons).
  • Neutron stars can emit streams of charged particles in a phenomenon called “pulsar wind.”

Causes of Emission

• Energy transitions: When a subatomic particle transitions from a higher energy state to a lower one, it emits the excess energy as radiation or particles.
• Instability: Radioactive nuclei are unstable and undergo decay to reach a more stable configuration, emitting energy and particles in the process.
• External interactions: Subatomic particles can be struck by other particles or radiation, leading them to emit energy or new particles.

Consequences of Emission

• Most of the light and energy we perceive around us arises from subatomic emission processes in stars, atoms, and molecules.
• Understanding subatomic emission is crucial for studying radioactive materials and designing nuclear reactions for energy production or other purposes.
• Studying the types and properties of emitted particles and radiation from cosmic sources helps us understand the composition and evolution of the universe.

Important concepts

• Quantum mechanics: Governs the behaviour of particles at the subatomic level and explains the probabilities associated with various emission processes.
• Energy levels: Electrons and other particles occupy specific energy levels within atoms. Transitions between these levels can lead to emissions.
• Radioactive decay: Different types of radioactive decay involve different emitted particles and energy levels.

Natural causes of emissions

• Stellar emissions: Stars like the Sun emit across the entire electromagnetic spectrum due to nuclear fusion at their core. This includes visible light, radio waves, infrared, ultraviolet, X-rays, and gamma rays.
• Atmospheric phenomena: Lightning strikes emit electromagnetic radiation, including visible light and radio waves. Aurora borealis and australis (Northern and Southern Lights) produce colourful visible light emissions due to charged particles interacting with the atmosphere.
• Forest fires and volcanic eruptions: These events release smoke, ash, and gases into the atmosphere. These particles scatter and absorb sunlight, impacting Earth’s energy balance. Volcanoes also emit various gases including sulfur dioxide and carbon dioxide.
• Biological processes: Living organisms like plants and animals release gases during respiration and other metabolic processes. These include carbon dioxide, methane, and nitrous oxide, all greenhouse gases contributing to climate change.

Artificial Causes of Emissions

• Fossil fuel combustion: Burning coal, oil, and natural gas for electricity generation, transportation, and industrial processes releases large amounts of greenhouse gases like carbon dioxide and nitrogen oxides, contributing significantly to climate change.
• Industrial processes: Manufacturing industries release various pollutants, including volatile organic compounds (VOCs), sulfur oxides, and particulate matter, impacting air quality.
• Agriculture: Fertilizer use, animal waste management, and agricultural land-use changes contribute to nitrous oxide emissions, a potent greenhouse gas.
• Deforestation: Cutting down trees reduces the carbon sequestration capacity of forests, leading to increased atmospheric carbon dioxide levels.

• Everything contains energy including all forms of matter and so all objects.
• Energy is evident in all forms of movement, interaction, and changes to the forms and properties of matter.
• Energy can exist in different forms, including thermal energy, chemical energy, electrical energy, and nuclear energy.
• At an atomic level, energy is evident for instance in the motion of electrons orbiting the nucleus of atoms.
• Energy can be transferred from one object to another and converted between different forms, but it cannot be created or destroyed.
• Everything in the universe uses energy of one form or another all the time.
• Energy is often described as potential energy or kinetic energy.
• Energy is measured in joules whilst power is measured in joules per second.

• Energy Carried by Photons: Electromagnetic radiation, including light, radio waves, X-rays, etc., consists of packets of energy called photons. The energy carried by a photon is directly related to its frequency. Higher frequencies correspond to higher energy photons.
• Electric Potential Energy: Electrostatic interactions involve the concept of electric potential energy. This energy is associated with the position of charged particles in an electric field. The difference in potential energy between two points determines the amount of work done when a charged particle moves between them.
• Electrical Energy: Electrical energy is the flow of electrical charges through a conductor. This flow of charge can be used to perform various tasks, such as powering lights, motors, and electronic devices. The amount of electrical energy transferred depends on the voltage (potential difference) and current flowing in the circuit.
• Magnetic Fields and Energy: Moving charges or changing electric fields create magnetic fields. Magnetic fields can also store energy. Electromagnets, for instance, use electrical energy to create a magnetic field, which can then be used to perform work, like lifting objects.
• Energy Transfer and Conversion: In electromagnetic interactions, energy can be transferred between different forms. For example, light energy (photons) can be converted into electrical energy in solar cells. Additionally, electrical energy can be used to create magnetic fields, storing energy, or converted into other forms like heat or light.

• Quantum Field Theory proposes a new way of looking at particles. Instead of individual particles existing on their own, it suggests that everything is made of vibrating energy fields that fill all of space and time. These fields are the fundamental entities, not the particles themselves.
• Particles as Excitations: When these fields get “rippled” or excited, they can create temporary bursts of energy that behave like particles. These are the particles we’re familiar with, like electrons or photons (light particles).
• Virtual vs. Real Particles: Some ripples are tiny and fleeting, lasting only a fraction of a second. These are called virtual particles. They can’t be directly detected but influence how real particles interact.
• Real Particles: Stronger ripples can create real particles that exist for longer and have definite properties like location and momentum. These are the particles we can measure in experiments.
• Adding Energy: Anything that adds energy to a field can create these ripples. This energy could come from another particle, an outside force, or even random fluctuations within the field itself.

• As an example imagine the field for light. This is the electromagnetic field. When this field gets a jolt of energy, it can create a ripple that produces a photon, a particle of light.