In physics, specifically in electromagnetism, the Lorentz force is the combination of electric and magnetic force on a point charge due to electromagnetic fields. A particle of charge q moving with a velocity v in an electric field E and a magnetic field B experiences a force of
Sutton SignWriting, or simply SignWriting, is a system of writing sign languages. It is highly featural and visually iconic, both in the shapes of the characters, which are abstract pictures of the hands, face, and body, and in their spatial arrangement on the page, which does not follow a sequential order like the letters that make up written English words. It was developed in 1974 by Valerie Sutton, a dancer who had, two years earlier, developed DanceWriting. Some newer standardized forms are known as the International Sign Writing Alphabet (ISWA).
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function assigning a vector to each point of space, called a vector field.
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole in the center of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.
In classical electromagnetism, Ampère's circuital law relates the circulation of a magnetic field around a closed loop to the electric current passing through the loop.
In mathematics and physics, the right-hand rule is a convention and a mnemonic, utilized to define the orientation of axes in three-dimensional space and to determine the direction of the cross product of two vectors, as well as to establish the direction of the force on a current-carrying conductor in a magnetic field.
Diver communications are the methods used by divers to communicate with each other or with surface members of the dive team. In professional diving, diver communication is usually between a single working diver and the diving supervisor at the surface control point. This is considered important both for managing the diving work, and as a safety measure for monitoring the condition of the diver. The traditional method of communication was by line signals, but this has been superseded by voice communication, and line signals are now used in emergencies when voice communications have failed. Surface supplied divers often carry a closed circuit video camera on the helmet which allows the surface team to see what the diver is doing and to be involved in inspection tasks. This can also be used to transmit hand signals to the surface if voice communications fails. Underwater slates may be used to write text messages which can be shown to other divers, and there are some dive computers which allow a limited number of pre-programmed text messages to be sent through-water to other divers or surface personnel with compatible equipment.
Faraday's law of induction is a law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (emf). This phenomenon, known as electromagnetic induction, is the fundamental operating principle of transformers, inductors, and many types of electric motors, generators and solenoids.
Cardistry is the performance art of card flourishing. Unlike card magic, cardistry is meant to be visually impressive and appear very hard to execute.
Several manual alphabets in use around the world employ two hands to represent some or all of the letters of an alphabet, usually as a part of a deaf sign language. Two-handed alphabets are less widespread than one-handed manual alphabets. They may be used to represent the Latin alphabet or the Cyrillic alphabet.
The Faraday paradox or Faraday's paradox is any experiment in which Michael Faraday's law of electromagnetic induction appears to predict an incorrect result. The paradoxes fall into two classes:
In electromagnetism, Fleming's right-hand rule shows the direction of induced current when a conductor attached to a circuit moves in a magnetic field. It can be used to determine the direction of current in a generator's windings.
Fleming's left-hand rule for electric motors is one of a pair of visual mnemonics, the other being Fleming's right-hand rule, for generators. They were originated by John Ambrose Fleming, in the late 19th century, as a simple way of working out the direction of motion in an electric motor, or the direction of electric current in an electric generator.
In electromagnetics, the catapult description of magnetic forces refers to when a current is passed through a loose wire in a magnetic field. The loose wire is then catapulted horizontally away from the magnetic field. This occurs due to the Lorentz force acting on the electric current in the wire due to the magnetic field.
American Sign Language (ASL), the sign language used by the deaf community throughout most of North America, has a rich vocabulary of terms, which include profanity. Within deaf culture, there is a distinction drawn between signs used to curse versus signs that are used to describe sexual acts. In usage, signs to describe detailed sexual behavior are highly taboo due to their graphic nature. As for the signs themselves, some signs do overlap, but they may also vary according to usage. For example, the sign for "shit" when used to curse is different from the sign for "shit" when used to describe the bodily function or the fecal matter.
Two-dimensional rotation can occur in two possible directions or senses of rotation. Clockwise motion proceeds in the same direction as a clock's hands relative to the observer: from the top to the right, then down and then to the left, and back up to the top. The opposite sense of rotation or revolution is anticlockwise (ACW) or counterclockwise (CCW). Three-dimensional rotation can have similarly defined senses when considering the corresponding angular velocity vector.
Fleming's rules are a pair of visual mnemonics for determining the relative directions of magnetic field, electric current, and velocity of a conductor.
An Esperanto manual alphabet is included as part of the Signuno project for manually coded Esperanto. Signuno is based on the signs of International Sign, but adapted to the grammatical system of Esperanto.
