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RC time constant. The RC time constant, denoted τ (lowercase tau ), the time constant (in seconds) of a resistor–capacitor circuit (RC circuit), is equal to the product of the circuit resistance (in ohms) and the circuit capacitance (in farads ): It is the time required to charge the capacitor, through the resistor, from an initial charge ...
Time constant. In physics and engineering, the time constant, usually denoted by the Greek letter τ (tau), is the parameter characterizing the response to a step input of a first-order, linear time-invariant (LTI) system. [1] [note 1] The time constant is the main characteristic unit of a first-order LTI system. It gives speed of the response.
Snell's law. Refraction of light at the interface between two media of different refractive indices, with n 2 > n 1. Since the velocity is lower in the second medium (v 2 < v 1 ), the angle of refraction θ 2 is less than the angle of incidence θ 1; that is, the ray in the higher-index medium is closer to the normal.
The coulomb (symbol: C) is the unit of electric charge in the International System of Units (SI). [1] [2] It is equal to the electric charge delivered by a 1 ampere current in 1 second and is defined in terms of the elementary charge e, at about 6.241 509 × 1018 e. [2] [1]
The one-way speed. Unidirectional light path in the aberration of light. Although the average speed over a two-way path can be measured, the one-way speed in one direction or the other is undefined (and not simply unknown), unless one can define what is "the same time" in two different locations. To measure the time that the light has taken to ...
In astrophysics and quantum physics a jiffy is, as defined by Edward R. Harrison, [13] the time it takes for light to travel one fermi, which is approximately the size of a nucleon. One fermi is 10−15 m, so a jiffy is about 3 × 10−24 s. It has also more informally been defined as "one light-foot", which is equal to approximately one ...
Photon energy is often measured in electronvolts. To find the photon energy in electronvolt using the wavelength in micrometres, the equation is approximately = since / = 1.239 841 984... × 10 −6 eV⋅m where h is the Planck constant, c is the speed of light, and e is the elementary charge.
186 282 mi. The light-second is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in one second, and is equal to exactly 299 792 458 m (approximately 983 571 055 ft or 186 282 mi ). Just as the second forms the basis for other units of time, the ...