S&J Chapter 23, pg 882 

Solutions: Solutions will be posted the day after homework is due


Q23.3 No. The magnetic force acts within the bar, but has no influence on the forward motion of the bar.
Q23.7 Yes. The induced eddy currents on the surface of the aluminum will slow the descent of the aluminum.
It will fall very slowly.

Q23.18 The motional emf between the wingtips cannot be used to run a light bulb. To connect the light, an
extra insulated wire would have to be run out along each wing, making contact with the wing tip. The
wings with the extra wires and the bulb constitute a single-loop circuit. As the plane flies through a
uniform magnetic field, the magnetic flux through this loop is constant and zero emf is generated. On
the other hand, if the magnetic field is not uniform, a large loop towed through it will generate pulses
of positive and negative emf. This phenomenon has been demonstrated with a cable unreeled from the
space shuttle.