PHYS1220 Lecture Notes - Lecture 4: Electric Field, Differential Equation, Point Particle
10 Oct 2018
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Document Summary
Del: a vector differential operator, acts like a vector. Divergence: a scalar called the divergence of a, or div a, shows if a vector field is growing or shrinking. Is a scalar: outgoing flux per unit volume. If the field is going outwards, is divergence; if inward, convergence. Relates the flux of an electric field through a closed surface to the total net charge enclosed by that surface. The velocity of a flowing liquid can be described by a three-dimensional vector field: v(x,y,z) The rate of the new mass per unit volume in the fluid k: k > 0: source, k < 0: sink. The divergence of r is the negative of the rate of change of density of the fluid: div > 0: expansion, div < 0: compression. For an incompressible fluid (such as water) Gives a vector of rotation i. e. if curl =/= 0, a paddle wheel in water will spin.
