- #1

OliskaP

- 38

- 7

**B**field from a balanced three-phase system.

Consider the following, shown in the picture below:

Lets say I want to calculate the value of

*B*at a distance

*r*(radius of my Amperian loop), the value of

*r*is big enough so that the loop encircles all three conductors.

From Ampere's law we have:

[itex]\oint_{c}\vec{B}\cdot d\vec{l} = \mu\times I_{enclosed}[/itex]

However, since the sum of the three currents = 0, i.e. net current out of the surface encircled by the curve C is equal to 0, indicates that the value of

*B*at point

*r*is also 0.

So what am I doing wrong, how should I apply Ampere's law to get the correct result?