## anonymous 3 years ago Why is this true? $\vec E \cdot d \vec l=E \hat i \cdot (dx \hat i +dy \hat j +dz \hat k)=E dx$ I understand the first part $\vec E \cdot d \vec l=E \hat i \cdot (dx \hat i +dy \hat j +dz \hat k)$ but how does that equal Edx?

1. anonymous

@zepdrix @hartnn

2. hartnn

i and j are perpendicular i and k are perpendicular

3. hartnn

i.i = i^2 = 1 i.j =0 i.k=0

4. anonymous

I'm sorry...but how did you determine that they were perpendicular?

5. hartnn

i , j and k are standard unit vectors. i is along x direction j is along y direction k is along z direction and axes are perpendicular to each other, right ?

6. anonymous

yes

7. hartnn

|dw:1361080799293:dw| any more doubts ?

8. anonymous

ahhhh.....nope...no more doubts =D