In the circuit shown in the figure, the switch \( S \) was initially open. Now the switch S is closed \( (t=0) \). If the current through the \( 10 \Omega \) resistor as a function of time after closing the switch is given by \( (A / B) e^{-t / \tau} A m p \) (where \( \tau=25 \mu sec \) ) find the value of \( A+B \).
