Magnetic Field in a Straight Current Carrying conductor
- In the above figures, note that there are current carrying conductors in opposite directions. In both cases, the current carrying conductor is intercepted by a cardboard placed at right angles to the current carrying conductor.
- There are some iron fillings sprinkled on the conductor.
- When current flows through the conductor, the iron filing arrange themselves along the magnetic field.
- We can see that the magnetic field in both cases is in opposite directions as is the current.
- The magnetic field produced by a current-carrying straight wire depends inversely on the distance from it and directly on the current passing through it.
- From this we see that the current carrying conductor produces a magnetic field around it. The direction of this magnetic field is given by Right Hand Thumb Rule.
Right Hand Thumb Rule
Suppose that you are holding a current-carrying straight conductor in your right hand such that the thumb points towards the direction of flow of current. Then, your fingers which wrap around the conductor indicate the direction of magnetic field lines (as shown in the figure)