# Calculating the Electric Field Strength at a certain point with multiple point charge

by fisixC
Tags: charge, electric, field, multiple, point, strength
 P: 54 1. The problem statement, all variables and given/known data Attached picture with the given variables and questions stated. 2. Relevant equations E = kq / (r^2) 3. The attempt at a solution I've taken found the linear electric field magnitudes in relationship to the point q1 = 3.37e-9 q2 = 6.74e-9 q3 = 3.92e-9 r1 = .647m r2 = 1.941m E1 = (k*(q1))/(r1) = 72.3540189055 E2 = (k*(q2))/(r2) = 16.0789708679 I am having difficulty figuring out how to calculate the third vector into the total, any thoughts? Attached Thumbnails
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 Quote by fisixC 1. The problem statement, all variables and given/known data Attached picture with the given variables and questions stated. 2. Relevant equations E = kq / (r^2) 3. The attempt at a solution I've taken found the linear electric field magnitudes in relationship to the point q1 = 3.37e-9 q2 = 6.74e-9 q3 = 3.92e-9 r1 = .647m r2 = 1.941m E1 = (k*(q1))/(r1) = 72.3540189055 E2 = (k*(q2))/(r2) = 16.0789708679 I am having difficulty figuring out how to calculate the third vector into the total, any thoughts?
Hi fisixC.

Pythagoras tells us that:
r32 = r12 + r22

The y-component of r3 is |r1|/|r3| .

The x-component of r3 is ‒|r2|/|r3| .

It may also help to notice that 1.941 = 3×0.647 .

Therefore,

|r1|/|r3| = |r1|/√(10)

|r2|/|r3| = 3|r1|/√(10)

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