In a chrging cirucit, after how many time constant will the energy stored in the capacitor reach one - half of its equilibrium value?

Explanation

`(q^(2))/(2C)=(1)/(2)(q_(0)^(2))/(2C)` or `q=(q_(0))/(sqrt(2))`
So, `(q_(0))/(sqrt2) = q_(0)(1-e^(-t//tau))` or `r = tau In((sqrt2)/(sqrt2 - 1)) = 1.23 tau`