Lenz Law (moving bar magnet and solenoid)

Drag a bar magnet towards or away from a solenoid and watch the induced current respond. Conventional current arrows run up the front and down the back of the windings, induced N and S poles are labelled on the solenoid faces, a galvanometer needle deflects with the emf, and the gap is annotated as attracting or repelling so students can check that the induced current opposes the change in flux. Controls for number of loops, magnet strength, pole orientation, and toggles for the magnet's own field lines and the traced solenoid field. A running commentary states whether flux is increasing or decreasing, alongside the equation for induced emf. Arrow keys nudge the magnet and F flips the poles.