title: Problem Set 10
(13.1)
(a)
{:.question} Estimate the diamagnetic susceptibility of a typical solid.
Starting from equation 12.15,
(b)
{:.question} Using this, estimate the field strength needed to levitate a frog, assuming a gradient that drops to zero across the frog. Express your answer in teslas.
From 12.7,
I'll assume the frog is 0.1 meters tall, has a mass of 0.1 kg, and a volume of
Thus the magnetic field is
(13.2)
{:.question} Estimate the size of the direct magnetic interaction energy between two adjacent free electrons in a solid, and compare this to the size of their electrostatic interaction energy. Remember that the field of a magnetic dipole
(13.3)
{:.question} Using the equation for the energy in a magnetic field, describe why:
(a)
{:.question} A permanent magnet is attracted to an unmagnetized ferromagnet.
(b)
{:.question} The opposite poles of permanent magnets attract each other.
(13.4)
{:.question} Estimate the saturation magnetization for iron at 0 K.
(13.5)
(a)
{:.question} Show that the area enclosed in a hysteresis loop in the
(b)
{:.question} Estimate the power dissipated if 1 kg of iron is cycled through a hysteresis loop at 60 Hz; the coercivity of iron is
(13.6)
{:.question} Approximately what current would be required in a straight wire to be able to erase a