Equipment: A flux model made from a 10 x 10 grid of nails and a square wire loop.

What it does: The model shows how the flux ('number' of field lines) through a closed loop changes as the angle between the field lines and the loop changes. The relation between flux and angle may be quantitatively determined if desired.

Concepts Demonstrated: Electric/magnetic flux through a closed loop as a function of angle.

Classroom assembly:

• Place the loop on the nail grid at a variety of angles to show that the number of field lines (nails) through the loop changes with angle.

Cautions: None.

Setup Time: Short.

Difficulty: Straightforward.

Visibility: Small. Can be passed around a small class.

Related demonstrations:

References:

Original Construction: The 'field lines' were made from 3.5" bright finishing nails hammered into a predrilled 10 x 10 grid with a .2125" spacing. The base of the nail 'field line' model is a block of 3.5" x 3.5" x .75" wood. The square wire loop was made from 16 gauge copper wire wound in a single turn around the nail grid to form an approximately 2.5" x 2.5" square loop. The loop was soldered closed for robustness.