# Interaction between current and magnetic field

1. Oct 27, 2013

### eddywalrus

According to Fleming's left hand rule, if the direction of a current that is running through a wire is perpendicular to the direction of the magnetic field that it is in, a force is acted on a wire that moves it in a direction that is both perpendicular to the wire and the field.

Why does the wire only move when the current is perpendicular to the magnetic field? Surely the magnetic fields interact somehow even if the current, crosses the magnetic field at, say, for example, 40 degrees?

2. Oct 27, 2013

### 256bits

It is easier to explain with fully perpendicular and parallel directions. At any angle other than those directions the current would have perpendicular and parallel components.

3. Oct 27, 2013

### Staff: Mentor

The direction of the force is always perpendicular to the directions of both the magnetic field and the current, even if the field and current are not perpendicular to each other.

The magnitude of the force depends on the angle between the directions of the field and current, and is maximum when they are perpendicular.