<Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (October 2017) (Learn how and when to remove this template message) </Td> </Tr> <P> If a change in the magnetic field of current i induces another electric current, i, the direction of i is opposite that of the change in i . If these currents are in two coaxial circular conductors l and l respectively, and both are initially 0, then the currents i and i must counter-rotate . The opposing currents will repel each other as a result . </P> <P> Lenz's law states that the current induced in a circuit due to a change or a motion in a magnetic field is so directed as to oppose the change in flux and to exert a mechanical force opposing the motion . </P> <P> Currents bound inside the atoms of strong magnets can create counter-rotating currents in a copper or aluminum pipe . This is shown by dropping the magnet through the pipe . The descent of the magnet inside the pipe is observably slower than when dropped outside the pipe . </P>

An induced magnetic field in a wire opposed the change in the external magnetic field