# What is the difference between the streamlines and trajectory functions?

In streamlines, the test charge used has no mass, or velocity. This means it follows the path of the electric field. Effectively what you should end up with is a limited version of the E-field. To calculate the resultant curves, Coulombs law is used. Streamlines can be drawn off of a voltage potential, or from a point in space. When drawn from a voltage potential, the streamlines will be placed leaving from both sides. From a point in space, the streamline will travel in the direction of increasing or decreasing field.

For the trajectories, a particle is used possessing charge, mass, and velocity. Thus the resultant path does not follow the electric field, but rather a path dictated by F = m a, where the electric field acts on the particle to slowly change its direction. Particles are launched with a user specified velocity, and direction.

Streamlines originating from one source and terminating at multiple grounds modeled on a PCB substrate in Coulomb 3D
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