A wire is bent into the shape of a circle. The radius
of the circle is 17 cm. A constant magnetic field
of magnitude 1,9 T is directed perpendicular to
the plane of the paper. Someone grabs the ends
of the wire and pulls it out, so the radius of the
circle shrinks to zero in a time of 1,7 s. Find the
magnitude of the average induced emf between the
ends of the wire.