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Meaning SI unit of measure alpha: alpha particle: angular acceleration: radian per second squared (rad/s 2) fine-structure constant: unitless beta: velocity in terms of the speed of light c: unitless beta particle: gamma: Lorentz factor: unitless photon: gamma ray: shear strain: radian
Voltage, also known as (electrical) potential difference, electric pressure, or electric tension is the difference in electric potential between two points. [1] [2] In a static electric field, it corresponds to the work needed per unit of charge to move a positive test charge from the first point to the second point.
This definition was abandoned in 1908 in favor of a definition based on the international ohm and international ampere until the entire set of "reproducible units" was abandoned in 1948. [ 15 ] A 2019 revision of the SI , including defining the value of the elementary charge , took effect on 20 May 2019.
Since the plot of I versus V is a straight line, then it is also true that for any set of two different voltages V 1 and V 2 applied across a given device of resistance R, producing currents I 1 = V 1 /R and I 2 = V 2 /R, that the ratio (V 1 − V 2)/(I 1 − I 2) is also a constant equal to R.
The perception is not linear to luminance, and relies on the context of the viewing environment (for example, see White's illusion). Brightness is a subjective sensation of an object being observed and one of the color appearance parameters of many color appearance models , typically denoted as Q {\displaystyle Q} .
where V is the scalar potential defined by the conservative field F. The electrostatic potential is simply the special case of this definition where A is time-invariant. On the other hand, for time-varying fields, − ∫ a b E ⋅ d ℓ ≠ V ( b ) − V ( a ) {\displaystyle -\int _{a}^{b}\mathbf {E} \cdot \mathrm {d} {\boldsymbol {\ell }}\neq ...
Field lines of a vector field v, around the boundary of an open curved surface with infinitesimal line element dl along boundary, and through its interior with dS the infinitesimal surface element and n the unit normal to the surface. Top: Circulation is the line integral of v around a closed loop C. Project v along dl, then sum.
Using the inverse hyperbolic function artanh, the rapidity w corresponding to velocity v is w = artanh(v/c) where c is the speed of light. For low speeds, by the small-angle approximation, w is approximately v / c. Since in relativity any velocity v is constrained to the interval −c < v < c the ratio v / c satisfies −1 < v / c < 1.