How do we know the point of 0 electric field is on the axis?

AI Thread Summary
The discussion centers on the assumption that the point of zero electric field between two charges lies along the axis connecting them. This is justified by the requirement that for two vectors to sum to zero, they must be equal in magnitude and opposite in direction, which occurs only along the line connecting the charges. Points off this axis cannot achieve a zero electric field because the vectors from each charge would not be antiparallel. The conversation highlights a lack of resources explaining this concept in textbooks or online. Understanding this principle is crucial for solving related physics problems effectively.
laser
Messages
104
Reaction score
17
Homework Statement
E=0
Relevant Equations
Electric field is a vector
In many homework problems I've encountered, they all seem to assume the electric field = 0 point is along the axis of the two charges. Intuitively it kind of makes sense, but I'm looking for a solid justification for it. In other words, why can't it be off the axis of the two charges? When setting up the problem, everyone seems to just assume it is on the axis.

Couldn't find any information about this in the book/online. Thanks!
Screenshot_2.png
 
Physics news on Phys.org
Draw the electric field at points outside the líne that joins q1 and q2
 
The only way to add two vectors to get zero is if they have equal magnitudes and are antiparallel.
 
  • Like
Likes MatinSAR and laser
… and the only places where they are antiparallel is where the two charges and the point of zero field all lie on the same line.
 
  • Like
Likes MatinSAR and laser
Thread 'Minimum mass of a block'
Here we know that if block B is going to move up or just be at the verge of moving up ##Mg \sin \theta ## will act downwards and maximum static friction will act downwards ## \mu Mg \cos \theta ## Now what im confused by is how will we know " how quickly" block B reaches its maximum static friction value without any numbers, the suggested solution says that when block A is at its maximum extension, then block B will start to move up but with a certain set of values couldn't block A reach...
TL;DR Summary: Find Electric field due to charges between 2 parallel infinite planes using Gauss law at any point Here's the diagram. We have a uniform p (rho) density of charges between 2 infinite planes in the cartesian coordinates system. I used a cube of thickness a that spans from z=-a/2 to z=a/2 as a Gaussian surface, each side of the cube has area A. I know that the field depends only on z since there is translational invariance in x and y directions because the planes are...
Thread 'Calculation of Tensile Forces in Piston-Type Water-Lifting Devices at Elevated Locations'
Figure 1 Overall Structure Diagram Figure 2: Top view of the piston when it is cylindrical A circular opening is created at a height of 5 meters above the water surface. Inside this opening is a sleeve-type piston with a cross-sectional area of 1 square meter. The piston is pulled to the right at a constant speed. The pulling force is(Figure 2): F = ρshg = 1000 × 1 × 5 × 10 = 50,000 N. Figure 3: Modifying the structure to incorporate a fixed internal piston When I modify the piston...
Back
Top