An RC circuit consists of a 5 uF capacitor, an 80,000 ohm resistor, and a 12-V…

An RC circuit consists of a 5 uF capacitor, an 80,000 ohm
resistor, and a 12-V battery. The switch is closed at t=0.
a) Find the time constant of the circuit.
b) Find the time to reach 90% of the maximum charge across the
capacitor.