posted by san juan .
An RC circuit contains a 3.9 kΩ resistor and a 5 µF capacitor. When the switch is first closed in the circuit, a maximum current of 1.5 mA flows in the circuit. Using Equation (1), find the time at which the current flow will have fallen to 1.0 mA.
I=V/R e^-t/rc is that you equation?
take the ln of each side
solve for time t.