A 2.5 W wire is curled into an elliptical loop with an area of 1.2 m2 and is placed horizontally on
a table where it is embedded in a 30 mT magnetic field that points upward. The ends of the
ellipse are then pulled, stretching it out and reducing the area to 0.1 m2
. As the ellipse
narrows, a current of 3.6 mA is generated in the wire. How long does it take to change the
ellipse’s shape?