# What is meant by "plane of the wire"?

In my textbook, it is given that

"The magnetic field produced due to current carrying circular wire at its center is perpendicular to the plane of the wire"

What is the meaning of "plane of the wire" in simple terms?

• "Circular wire", a circle is always on a unique plane in space. Jan 18, 2021 at 9:20

## 2 Answers

Imagine having the circular wire in front of you. If it laid on your desk, then the plane of the wire would be a kind of virtual "sheet" that goes through the entire wire, hovering just above your desk, parallel to the upper surface of the desk. If you pressed the circular wire into the wall, then the surface of the wall and the wire would be in the same plane.

Some other examples that might help - when you write on a piece of paper, that sheet of paper (as long as it's completely flat) is part of the plane of the writing. When you cut a lemon in half and hold the cut slices together, the plane of the cut is like a virtual "sheet" that is flat, passing between the two halves of the lemon.

Put simply, the "plane" is the 2-dimensional flat surface which contains the circular wire.

The illustrations (ignore the math for now) in this wikipedia article may help you visualise a plane. https://en.wikipedia.org/wiki/Plane_%28geometry%29?wprov=sfla1

I think this clarifies the situation - the green wire circle lies on the plane - the red arrow is normal (or perpendicular) to the plane (of the circle). The magnetic field is rotationally sysmetric around this axis and will have the direction shown when the current in the wire is flowing anticlockwise as viewed from the direction shown