RL circuit

Hi. Can someone please show me how to do this problem? "How long does it take for the current in an RL circuit with R = 130 ohms and L = 63 mH to reach half its final value?" Thank you.

RL circuit

Hi. Can someone please walk me through how to do this problem? "Consider an RL circuit in which there's a 9.0 V battery, R = 5.5 ohms, L is unknown, and there's a switch that can be open or closed. When the switch is closed, the current in the circuit is observed to increase from 0 to 0.22 A in 0.15 seconds. (a) What is the inductance L? (b) How long after the switch is closed does the current have the value 0.40 A? (c) What is the maximum current that flows in this circuit? Thank you!

energy stored in magnetic field

Hi. Can someone please show me how to do the following problem? "Given an RL circuit in which there's a 9.0 V battery, R = 5.5 ohms, L = 6.1 mH, and there's a switch that can be opened or closed, how much energy is stored in the inductor after the switch has been closed a long time?" Thank you.

transformers

Hi. Can someone please show me how to do the following problem? "A transformer with a turns ratio (secondary/primary) of 1:13 is used to step down the voltage from a 120-V wall socket to be used in a battery recharging unit. What is the voltage supplied to the recharger?" Thank you.

RC circuit

Hi. Can someone please walk me through how to do the following problem? "The capacitor in an RC circuit (R = 120 ohms, C = 45 micro-F) is initially charged. Find (a) the charge on the capacitor and (b) the current in the circuit one time constant after the circuit is connected to a 9.0-V battery." Thank you.