Consider a square drum with a vibrating membrane. When the drum is struck exactly at the center of the membrane, the oscillations will be described by a 1 vertical displacement u(x, y, t) given by

In the circuit, the switch s has been open for a long time and r = 125 kohm. it is then suddenly closed. (a) determine the time constant before the switch is closed. s (b) determine the time constant after the switch is closed. _ s (c) let the switch be closed at t = 0. find the current in the switch as a function of time. (use t for time. express your answer in milliamps and seconds.) i(t) =_