Electricity and magnetism point charges problem

[ravsau]

Homework Statement

Four point charges have equal magnitudes. three are positive and one is negative, as the diagram shows. they are fixed in place on the same straight line, and adjacent charges are equally separated by a distance d. consider the net electrostatic force acting on each charge. calculate the ratio of the largest to the smallest net force.


(+) ------- d --------- (+) ------- d --------- (+) -------- d --------- (-)

A B C D

Homework Equations

The Attempt at a Solution

This questions has no numbers so I am confused

 

[Andrew Mason]

Homework Statement

Four point charges have equal magnitudes. three are positive and one is negative, as the diagram shows. they are fixed in place on the same straight line, and adjacent charges are equally separated by a distance d. consider the net electrostatic force acting on each charge. calculate the ratio of the largest to the smallest net force.


(+) ------- d --------- (+) ------- d --------- (+) -------- d --------- (-)

A B C D

Homework Equations

The Attempt at a Solution

This questions has no numbers so I am confused

You don't need numbers. Let the first three charges be +q and the fourth -q. What is the force of B on A? (hint: Coulomb's law).

Once you work that out, calculate the forces of C on A and of D on A and add them all up vectorily. Then work out the forces on B, C and D.

AM