how many time constants will elapse before the power delovered by the battery drops to half of its maximum value in an RC circuit ?

Explanation

`Power = CV^2 = q xx V`
` Now, qV/2 = qV xx e^(-t/rc)`
` rArr 1/2 = e^(-t/rc)`
` rArr t/rc = - In (0.5) `
` = -(-0.69) = 0.69.`