# Dictionary search results

Showing 1-43 of 43 results

## equation US English

A statement that the values of two mathematical expressions are equal (indicated by the sign =)

## gas equation US English

The equation of state of an ideal gas, PV = nRT, where P = pressure, V = volume, T = absolute temperature, R = the gas constant, and n = the number of moles of gas

## wave equation US English

A differential equation expressing the properties of motion in waves

## Drake equation US English

A speculative equation that gives an estimate of the likelihood of discovering intelligent extraterrestrial life in the galaxy, expressed as the product of a series of factors such as the number of stars, the fraction of stars with planets, the fraction of planets on which life evolves, the average lifetime of a civilization, etc. It was formulated by the US astronomer Frank Drake in 1961

## field equation US English

One of Maxwell's equations.

## human equation US English

The component of a situation, etc., which arises from or relates to human influence or behaviour.

## linear equation US English

An equation between two variables that gives a straight line when plotted on a graph

## master equation US English

An equation which expresses the evolution in time of the probability distribution of the possible states of a system in terms of the microscopic processes involved.

## polar equation US English

An equation of a curve or surface expressed in polar coordinates.

An equation which states the relationship between the amount of power returning to a radar receiver and various factors affecting this (as the transmitter power, and the distances from the transmitter to the target and from the target to the receiver).

## Abelian equation US English

A polynomial equation whose Galois group is commutative or (in early use) cyclic.

## Mathieu's equation US English

A differential equation arising in connection with elliptically symmetrical systems, having the form d2 y/dx 2 + (a + b cos 2x)y = 0, where a and b are constants.

## personal equation US English

The correction required in scientific observations (originally in astronomy) to compensate for the habitual inaccuracy of an individual observer; (in extended use) the component of a situation which relates to or arises from an individual's personal qualities.

## Planck's equation US English

= Planck's formula.

## Poisson's equation US English

The generalization of Laplace's equation produced by replacing the zero of the right-hand side by a constant or, more generally, by a specified function of position.

An equation of the second degree; specifically an equation of the form ax 2 + bx + c = 0, where a, b, and c are constants and x is unknown.

## continuity equation US English

= equation of continuity.

## differential equation US English

An equation involving derivatives of a function or functions

## Diophantine equation US English

A polynomial equation with integral coefficients for which integral solutions are required

## equation of state US English

An equation showing the relationship between the values of the pressure, volume, and temperature of a quantity of a particular substance

## equation of time US English

The difference between mean solar time (as shown by clocks) and apparent solar time (indicated by sundials), which varies with the time of year

## parametric equation US English

Any of a set of equations each of which expresses one of the coordinates of a curve or surface as a function of one or more parameters.

## Poiseuille's equation US English

An equation expressing the relation between the volume V of fluid flowing per second through a long narrow cylinder under conditions of Poiseuille flow, the viscosity of the fluid, and the dimensions of the cylinder, namely V = πr 4 p/8ηl, where p is the difference in pressure between the ends of the cylinder, η is the viscosity of the fluid, l is the length of the cylinder, and r is its radius.

## reciprocal equation US English

(Originally) an equation whose roots can be divided into pairs of numbers, each the reciprocal of the other; (equivalently) an equation which is unchanged if the variable is replaced by its reciprocal (now rare); (in later use) an equation involving a reciprocal.

## regression equation US English

An equation relating the expected value of a dependent variable to the value of one or more independent variables.

## Richardson equation US English

An equation for the maximum current density of electrons emitted from a hot metal surface in terms of the temperature and work function of the surface.

## Schrödinger equation US English

A differential equation that forms the basis of the quantum-mechanical description of matter in terms of the wavelike properties of particles in a field. Its solution is related to the probability density of a particle in space and time

## characteristic equation US English

Mathematics. More fully Gaussor Gauss's characteristic equation. An equation expressing the curvature of a surface in terms of certain parameters of the surface.

## Navier–Stokes equation US English

Each of the one-dimensional equations of motion for a viscous fluid. Also: the vector equation combining these, which may be written d V/d t = − 1/ρ∇p + F + ν∇2 V + V) where V is the fluid velocity, ρ the density, p the pressure, F the total force per unit mass, and ν the kinematic viscosity.

## partial differential equation US English

An equation containing one or more partial derivatives

## Richardson–Dushman equation US English

The Richardson equation, especially in one or other of its later representations.

## equation of the first order, US English

An equation involving only the first derivative, second derivative, etc.

## the equation in equation US English

A situation or problem in which several factors must be taken into account

## Maxwell's equations US English

A set of four linear partial differential equations that summarize the classical properties of the electromagnetic field

## simultaneous equations US English

Equations involving two or more unknowns that are to have the same values in each equation

## Onsager equation in Onsager US English

Physical Chemical Onsager equation noun also Onsager's equation an equation that relates the conductance of an electrolytic solution to that of the pure solvent.

## Pell equation in Pell3 US English

In full Pell equation, Pell's equation. A Diophantine equation of the form y 2 − ax 2 = 1, where x and y are integer variables, and a is an integer constant.

## Pell's equation in Pell3 US English

In full Pell equation, Pell's equation. A Diophantine equation of the form y 2 − ax 2 = 1, where x and y are integer variables, and a is an integer constant.

## equation of the first order, in equation US English

An equation involving only the first derivative, second derivative, etc.

## Black-Scholes equation in Black-Scholes US English

Attributive Designating a mathematical model for calculating the value of stock options, as Black–Scholes model, Black–Scholes option pricing model, etc. Also: designating the formula or equation used in this model, as Black-Scholes equation, Black-Scholes formula, etc.

## equation of the first order, second order, etc. in equation US English

An equation involving only the first derivative, second derivative, etc.

## Gaussor Gauss's characteristic equation in characteristic equation US English

Mathematics. More fully Gaussor Gauss's characteristic equation. An equation expressing the curvature of a surface in terms of certain parameters of the surface.