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Negative refraction. Negative refraction is the electromagnetic phenomenon where light rays become refracted at an interface that is opposite to their more commonly observed positive refractive properties. Negative refraction can be obtained by using a metamaterial which has been designed to achieve a negative value for (electric) permittivity ...
Health threats from cosmic rays are the dangers posed by cosmic rays to astronauts on interplanetary missions or any missions that venture through the Van-Allen Belts or outside the Earth's magnetosphere. [1] [2] They are one of the greatest barriers standing in the way of plans for interplanetary travel by crewed spacecraft, [3] [4] [5] but ...
A negative-index metamaterial causes light to refract, or bend, differently than in more common positive-index materials such as glass lenses. Negative-index metamaterial or negative-index material ( NIM) is a metamaterial whose refractive index for an electromagnetic wave has a negative value over some frequency range. [1]
A cold cathode [1] is a cathode that is not electrically heated by a filament. [note 1] A cathode may be considered "cold" if it emits more electrons than can be supplied by thermionic emission alone. It is used in gas-discharge lamps, such as neon lamps, discharge tubes, and some types of vacuum tube. The other type of cathode is a hot cathode ...
Comparison of positive and negative birefringence : In positive birefringence (figure 1), the ordinary ray (p-polarisation in this case w.r.t. magenta-coloured plane of incidence), perpendicular to optic axis A is the fast ray (F) while the extraordinary ray (s-polarisation in this case and parallel to optic axis A) is the slow ray (S).
Electric charge (symbol q, sometimes Q) is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be positive or negative. Like charges repel each other and unlike charges attract each other. An object with no net charge is referred to as electrically neutral.
Atmospheric electricity describes the electrical charges in the Earth's atmosphere (or that of another planet ). The movement of charge between the Earth's surface, the atmosphere, and the ionosphere is known as the global atmospheric electrical circuit. Atmospheric electricity is an interdisciplinary topic with a long history, involving ...
The elementary charge e, i.e. the negative charge on a single electron or the positive charge on a single proton: 10 −18: atto-(aC) ~ 1.8755 × 10 −18 C: Planck charge: 10 −17: 1.473 × 10 −17 C (92 e) – Positive charge on a uranium nucleus (derived: 92 x 1.602 × 10 −19 C) 10 −16: 1.344 × 10 −16 C: Charge on a dust particle in ...