According to the law proposed by the Russian physicist Heinrich Lenz, from experimental results, the induced current has the opposite direction of the variation of the magnetic field that generates it.
- If there is a decrease in magnetic flux, the induced current will create a magnetic field with the same direction as the flux;
- If the magnetic flux increases, the induced current will create a magnetic field opposite the direction of the flux.
If we take as an example, a loop placed on the plane of a page and subjected it to a magnetic flux that has direction perpendicular to the page and with an input direction on the sheet.
- If is positive, ie if the magnetic flux increases, the induced current will be counterclockwise;
- If negative, ie if the magnetic flux decreases, the induced current will be clockwise.