Visualizing Electric Flux

Highlights of the activity

1. This computer visualization activity is designed to help students visualize the flux of the electric field of a point charge through a cube.
2. Students use Maple/Mathematica to explore the effects of putting a point charge at various places inside, outside, and on the surface of a cubical Gaussian surface.
3. The wrap-up discussion highlights the “discovery” of Gauss's Law by using Maple/Mathematica to calculate the total flux through the cube.

Reasons to spend class time on the activity

Middle-division students have some knowledge of Gauss's Law from their introductory courses, but many have difficulty visualizing how physical quantities like the distance of the charge from a side of the box or the angle between the side of the box and the direction of the electric field contribute to the integrand. This activity allows students to move the point charge around relative to the box and allows students to see the calculation Maple does to find the flux through each side and the total flux. Students see that the total flux is $\dfrac{q}{\epsilon_{0}}$ when the charge is inside the box, $0$ when it is outside the box, and (can you guess??) when it is on a face, edge, or vertex of the box.

Reflections

• Reflections from the original implementation.

• Reflections from "official" adapters/adopters.

• Reflections from the general public.

Instructor's Guide

• Wiki version

Maple Worksheet

vffluxem.mw (Maple 13)

vffluxem.mws (Maple 11 Classic)

Mathematica Notebook

vffluxem.nb