Q2: An instrument based on induced emf has been used to measure projectile speeds up to 6 km/s. A small mag- net is imbedded in the projectile as shown in Figure P31.2. The projectile passes through two coils sepa- rated by a distance d. As the projectile passes through each coil, a pulse of emf is induced in the coil. The time interval between pulses can be measured accu- rately with an oscilloscope, and thus the speed can be determined.
(a) Sketch a graph of DV versus t for the arrangement shown. Consider a current that flows counterclockwise as viewed from the starting point of the projectile as positive. On your graph, indicate which pulse is from coil 1 and which is from coil 2.
(b) If the pulse separation is ms and d = m, what is the projectile speed?
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