Question

A 38.0-V battery with negligible internal resistance, a 48.0-Ohm resistor, and a 1.45-mH inductor with negligible resistance are all connected in series with an open switch. The switch is suddenly closed. Part A How long after closing the switch will the current through the inductor reach one-half of its maximum value? Part B How long after closing the switch will the energy stored in the inductor reach one-half of its maximum value?

Answer 1

As the switch is closed, current begins to flow around the circuit increasing toward a maximum value given by Ohm's Law We want to find the time when the current is half of the maximum 2R) A In Substitute the numerical values t--( 1.45x10-3 H = 2.09 × 10-5 s 2.09x10 s40 10-6 we want the energy to be half of its maximum use formula for current Substitute the numerical values 48Ω 48Ω 1.45x10 H 0.29289 -| 480 1.45x10-3 H In (0.29289)