In Fig. $28-57$ , the two ends of a U-shaped wire of mass $m=$ 10.0 $\mathrm{g}$ and length $L=20.0 \mathrm{cm}$ are immersed in mercury (which is a
conductor). The wire is in a uniform field of magnitude $B=0.100 \mathrm{T}$ . A switch (unshown) is rapidly closed and then reopened, sending a
pulse of current through the wire, which causes the wire to jump up-
ward. If jump height $h=3.00 \mathrm{m}$ , how much charge was in the pulse?
Assume that the duration of the pulse is much less than the time
of flight. Consider the definition of impulse (Eq. $9-30$ ) and its
relationship with momentum (Eq. $9-31 )$ . Also consider the
relationship between charge and current (Eq. $26-2 )$ .