This interactive begins with a rotating wire loop connected to a voltmeter. The loop is immersed in a magnetic field which has two forms. Using the Field Controls panel, you can choose a uniform field (the default) or the field created by a bar magnet. If the field is uniform, you can use the Field Strength slider bar to set its magnitude.

The Loop Controls panel allows you to change the loop's radius (and thereby its area). By default, the loop rotates automatically, as if connected to a motor. You can change the speed at which it rotates via the Rotation Speed slider bar. Alternatively, if you choose the Crank option, you control the loop directly: slide the Crank bar to the loop's right up and down with your mouse to make the loop move.