- #1

perplexabot

Gold Member

- 329

- 5

## Main Question or Discussion Point

Hello all.

I am trying to change:

E = (1/r) ar

To rectangular coordinate system. Where ar is a unit vector.

So I know r = √(x^2 + y^2)

i also think ar = ax+ay, where ax and ay are unit vectors along the x axis and y axis respectively.

So that would give me: E = (1/√(x^2 + y^2)) (ax + ay) = ax/√(x^2 + y^2) + ay/√(x^2 + y^2)... Which is wrong.

The correct answer is: (x ax)/(x^2 + y^2) + (y ay)/(x^2 + y^2)

So what am I doing wrong? Thank you.

I am trying to change:

E = (1/r) ar

To rectangular coordinate system. Where ar is a unit vector.

So I know r = √(x^2 + y^2)

i also think ar = ax+ay, where ax and ay are unit vectors along the x axis and y axis respectively.

So that would give me: E = (1/√(x^2 + y^2)) (ax + ay) = ax/√(x^2 + y^2) + ay/√(x^2 + y^2)... Which is wrong.

The correct answer is: (x ax)/(x^2 + y^2) + (y ay)/(x^2 + y^2)

So what am I doing wrong? Thank you.