1 . a) Your study buddy is explaining that since \" flux \" means \"to flow\", t
ID: 2000462 • Letter: 1
Question
1 . a) Your study buddy is explaining that since " flux " means "to flow", that electric flux is like a river current of the electric field moving through some defined area. Do you agree or not? Explain briefly. b) Looking over some online notes you found about electric flux, you see that the author has written that electric flux is the electric field per unit area, somewhat analogous to pressure which is force per unit area. Are you content with this definition? Explain briefly. c) Consider a charged cube, with a uniform volumetric charge distribution throughout. Explain briefly how you would use Coulomb's Law to find the electric field at some point a distance r from the center of the cube, where that point lies outside of the cube. Is this problem conducive to solving with Gauss’s Law? Why or why not?
Explanation / Answer
(a) Flux means flow just like a river flow. In fluid dynamics the river flow is denoted by mass flux or mass flowrate which is the volume of fluid flowing through an area. This is because volume and mass are related by density.
Similarly in Electric flux electric field lines are flowing through an area.
(b) Yes exactly. When mass flows or water flows or hits an area it exers pressure which is force / unit area and pressure itself is anologous to mass flux. Similarly Electric flux is the electric field per unit area.
(c) Electric field at point outside cube at a distance r from centre of cube is difficult to be calculated with coloumbs law because, we have to take small volume elements and and find field at the point individually. THen integrate these elements vectorially to get the resultant field. This is a huge task.
But by guass law due to symmetry from centre of cube and charge distribution in the cube also is symmetrical we have
integral ( E.ds) = qin /(epsilon)
Still we will be unable since the cube is symmetrical in 3 directions not in every direction. So Field normal to a face of cube at distance r is different from field at same distance from centre towards corner direction.
The integral holds, but we can not specifically calculate field. We have to rely on coulumbs law only.
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