2. The voltage across the plates of a capacitor at any time t seconds is given by V=Ve-t/CR v = Ve t/CR , where V, C and R are constants. Given V = 250 volts, C = 0.15 x 10 6 farads and R = 3.5 10 ohms, (a) find the initial rate of change of voltage, and (b) the rate of change of voltage after 0.7 s.