A resistor and a capacitor are connected as shown in fig. 5.178. The capacitor is originally given a charge of `5.0muC` and then discharged by closing the swtich at t =0.
a. At what tiem will be charge be equal to `0.50muC`?
b. What in the current at this time?

Explanation

a. For the time t, we have
`t = -RC "in" (q)/(Q)`
`=-10xx10^6xx1.0xx10^(-6)`
`"in" (0.50)/(5.0) = 23s`
This is 2.3 times the constant RC =10S
b. `Q = 5.0muC = 5.010^(-6)C`
`I = (Q)/(RC)e^(-t//RC) =(5.0xx10^(-6))/(10)e^(-23//10)=5.0xx10^(-8)C`