Black-body radiation 1970-01-01
Black-body radiation refers to the electromagnetic radiation emitted by a perfect black body, which is an idealized physical object that absorbs all incident radiation, regardless of frequency or angle. When a black body is in thermal equilibrium, it emits radiation in a characteristic spectrum that depends solely on its temperature. Key characteristics of black-body radiation include: 1. **Spectrum**: A black body emits radiation across a continuous spectrum of wavelengths, with the intensity peaking at a particular wavelength that is determined by its temperature.
Black body 1970-01-01
A black body is an idealized physical object that absorbs all incoming radiation, regardless of the frequency or angle of incidence. In other words, a black body is a perfect emitter and absorber of thermal radiation. It does not reflect or transmit any radiation, which distinguishes it from real-world objects that typically reflect some light. Key characteristics of a black body include: 1. **Absorption**: A black body absorbs 100% of the electromagnetic radiation that falls on it.
Bond albedo 1970-01-01
Bond albedo is a measure of the reflectivity of an astronomical body, specifically in the context of the entire hemisphere of that body. It quantifies the fraction of total incoming solar energy that is reflected back into space by that body, taking into account all wavelengths of light and all angles of incidence. This is different from the more commonly known geometrical albedo, which only considers light reflected at a specific angle, typically from a direct overhead view.
Cloak of invisibility 1970-01-01
The "Cloak of Invisibility" is a fictional magical item, most famously associated with the "Harry Potter" series by J.K. Rowling. In the story, it is a special cloak that renders the wearer invisible to others. The cloak is one of the three Deathly Hallows, which are powerful magical objects in the series.
Coherence length 1970-01-01
Coherence length is a measure of the length over which a coherent wave, such as light or other electromagnetic radiation, maintains a consistent phase relationship. It quantifies the distance over which the wave can be considered to have a uniform phase, meaning that the wave exhibits stable interference patterns. In the context of laser light, which is highly coherent, the coherence length can be quite long, sometimes extending several meters.
Coherence time 1970-01-01
Coherence time is a measure of the time duration over which a quantum system maintains its quantum coherence. In quantum mechanics, coherence refers to the ability of a quantum state to exhibit interference effects, which is crucial for many quantum phenomena and applications, such as quantum computing, quantum cryptography, and quantum optics.
Cosmic background radiation 1970-01-01
Cosmic background radiation, also known as cosmic microwave background (CMB) radiation, is the afterglow of the Big Bang that occurred approximately 13.8 billion years ago. It is pervasive throughout the universe, filling all of space and is a critical piece of evidence for the Big Bang theory of cosmology. Here are some key points about cosmic microwave background radiation: 1. **Nature of CMB**: CMB radiation is a type of electromagnetic radiation that is uniform in all directions.
Creeping wave 1970-01-01
Creeping waves, also known as "creeping line waves" or "surface waves," refer to a type of electromagnetic wave propagation that occurs along the surface of a dielectric material, such as the surface of a conductor or the interface between two media with different electromagnetic properties. These waves "creep" along the surface rather than propagating freely through the bulk of the material or space.
Cyclotron radiation 1970-01-01
Cyclotron radiation is the electromagnetic radiation emitted by charged particles, such as electrons or ions, when they are accelerated in a magnetic field. This phenomenon occurs because when a charged particle moves through a magnetic field, it experiences a force that causes it to follow a curved path, typically in a circular or spiral trajectory. As these charged particles accelerate (change direction), they emit radiation due to the loss of energy.
Cyclotron turnover 1970-01-01
Cyclotron turnover refers to the phenomenon observed in the context of plasma physics and astrophysics, particularly in the behavior of charged particles in a magnetic field. When charged particles, such as electrons or ions, move through a magnetic field, they experience a Lorentz force that causes them to spiral in circular paths, known as cyclotron motion. The term "turnover" can imply the frequency or rate at which these particles complete their circular paths, generally referred to as the cyclotron frequency.
Directed-energy weapon 1970-01-01
A directed-energy weapon (DEW) is a type of weapon that emits energy in an aimed direction and can incapacitate, damage, or destroy targeted objects or personnel. Unlike conventional weapons that rely on kinetic energy (such as bullets or missiles) or explosive energy (such as bombs), DEWs utilize focused forms of energy such as: 1. **Laser Systems**: These weapons use focused beams of light to damage or disable targets, such as drones or missiles.
Directional-hemispherical reflectance 1970-01-01
Directional-hemispherical reflectance (DHR) refers to a measurement of reflectance that characterizes how a surface reflects incoming light in a specific directional manner across a hemispherical angle. It is particularly important in fields like optics, materials science, and remote sensing because it provides insights into the reflective properties of materials when they are lit by a light source from a particular direction.
Discrete ordinates method 1970-01-01
The Discrete Ordinates Method (DOM) is a numerical technique used primarily to solve radiative transfer equations (RTEs) in various applications, including heat transfer, astrophysics, atmospheric science, and optical engineering. In essence, it is a way to model how radiation—such as light or thermal energy—propagates through a medium.
Draper point 1970-01-01
The Draper Point is a term used in the field of planetary science that refers to a specific temperature threshold, typically around 100°C (212°F), which is the maximum surface temperature at which liquid water can exist on a planetary body at certain pressure conditions. This concept is often discussed in the context of habitability and the search for extraterrestrial life, as it pertains to the stability of liquid water, a critical ingredient for life as we know it.
Driven guard 1970-01-01
The term "Driven Guard" could refer to different concepts depending on the context, but it's not a widely recognized term in any specific domain. Here are a few possibilities: 1. **In Sports**: In basketball, for example, a "driven guard" could refer to a player who is aggressive in driving toward the basket, often using their speed and agility to penetrate the defense.
Effective temperature 1970-01-01
Effective temperature is a concept used in various scientific fields, particularly in astronomy and climatology, to describe the temperature of an object or system, taking into account various factors that affect its energy balance. 1. **Astronomy**: In the context of stars, the effective temperature is the temperature that a black body (an idealized physical body that absorbs all incoming radiation) would need to emit the same amount of total energy as the star.
Electromagnetic environment 1970-01-01
The term **electromagnetic environment** refers to the totality of electromagnetic fields and radiation present in a given area. This environment is influenced by both natural sources and human-made sources of electromagnetic energy. ### Components of the Electromagnetic Environment: 1. **Natural Sources**: - **Cosmic Radiation**: High-energy particles from outer space. - **Earth’s Magnetic Field**: Generated by the Earth’s core.
Electromagnetic forming 1970-01-01
Electromagnetic forming (EMF) is a manufacturing process that utilizes electromagnetic forces to shape or form conductive materials, typically metals. This technique is particularly valued for its ability to manipulate materials with high precision and minimal mechanical contact. ### Key Features of Electromagnetic Forming: 1. **How It Works**: - The process involves generating a rapidly changing magnetic field, typically through a coil or solenoid that surrounds the workpiece.
Electromagnetic pulse 1970-01-01
An Electromagnetic Pulse (EMP) is a burst of electromagnetic radiation that can disrupt or damage electronic equipment and electrical systems. EMPs can be generated by various sources, including: 1. **Nuclear Explosions:** A nuclear detonation at high altitudes can produce a powerful EMP that can affect a vast area, potentially damaging or destroying electronic devices and infrastructure.
Electromagnetic reverberation chamber 1970-01-01
An electromagnetic reverberation chamber is a specialized testing environment that is designed to create a controlled electromagnetic field for the purpose of evaluating the performance of electronic devices, components, and systems in a consistent and repeatable manner. These chambers are used for assessing various parameters such as electromagnetic compatibility (EMC), wireless communications performance, and antenna characteristics.