Physics · Ch 3 — Magnetism and Magnetic Effects of Electric Current
Maxwell's Right Hand Cork Screw Rule
Maxwell's Right Hand Cork Screw Rule
As an equivalent alternative to the thumb rule, Maxwell's right hand cork screw rule uses the image of driving a right-handed screw with a screwdriver: if the screw advances in the direction of the current, then the direction in which the screwdriver must be turned to advance it gives the direction of the magnetic field circling the current. Both rules always give the sa …
What this figure shows. A right-handed screw is drawn being turned by a screwdriver so that it advances along the direction of current flow I; the rotational sense of the turning screw (shown by a curved arrow) is the direction of the magnetic field B circling the current, giving exactly the same field direction as the right-han …
Worked out. Given a diagram of a straight wire where the field lines are shown pointing out of the page on one side and into the page on the other side of the wire, applying the right-hand rule in reverse (matching the fingers' curl to the shown field sense) shows the current in the wire must be flowing upwards. This is simply the right-hand rule used to infer the current direction from an already-known field pattern, rather than the more usual direction of predicting the field …