Search results
Results from the WOW.Com Content Network
A velocity potential is not unique. If ϕ is a velocity potential, then ϕ + f(t) is also a velocity potential for u, where f(t) is a scalar function of time and can be constant. Velocity potentials are unique up to a constant, or a function solely of the temporal variable. The Laplacian of a velocity potential is equal to the divergence of the ...
Electromagnetic field (arbitrary unit) of a positive point charge moving at constant speed. When =, the electromagnetic field reduces to electrostatic field (in blue).Due to its insignificance at large distance, this field is ignored in high energy physics when computing electromagnetic radiation power.
Position vectors r and r′ used in the calculation. The starting point is Maxwell's equations in the potential formulation using the Lorenz gauge: =, = where φ(r, t) is the electric potential and A(r, t) is the magnetic vector potential, for an arbitrary source of charge density ρ(r, t) and current density J(r, t), and is the D'Alembert operator. [2]
Position vectors r and r′ used in the calculation. Retarded time t r or t′ is calculated with a "speed-distance-time" calculation for EM fields.. If the EM field is radiated at position vector r′ (within the source charge distribution), and an observer at position r measures the EM field at time t, the time delay for the field to travel from the charge distribution to the observer is |r ...
The scalar potential is an example of a scalar field. Given a vector field F, the scalar potential P is defined such that: [1] = = (,,), where ∇P is the gradient of P and the second part of the equation is minus the gradient for a function of the Cartesian coordinates x, y, z. [a] In some cases, mathematicians may use a positive sign in front ...
Consider a scalar quantity φ = φ(x, t), where t is time and x is position. Here φ may be some physical variable such as temperature or chemical concentration. The physical quantity, whose scalar quantity is φ, exists in a continuum, and whose macroscopic velocity is represented by the vector field u(x, t).
An example of a scalar quantity is temperature: the temperature at a given point is a single number. Velocity, on the other hand, is a vector quantity. Other examples of scalar quantities are mass, charge, volume, time, speed, [2] pressure, and electric potential at a point inside a medium.
Trajectory of a particle with initial position vector r 0 and velocity v 0, subject to constant acceleration a, all three quantities in any direction, and the position r(t) and velocity v(t) after time t. The initial position, initial velocity, and acceleration vectors need not be collinear, and the equations of motion take an almost identical ...