34. RLC Series Circuit. In the study of an electrical circuit consisting of a resistor, capacitor, inductor, and an electromotive force (see Figure 4.9), we are led to an initial value problem of the form
(20)$$egin{array}{l}{L frac{d I}{d t}+R I+frac{q}{C}=E(t)} \\ {q(0)=q_{0}} \\{I(0)=I_{0}}end{array}$$
where L is the inductance in henrys, R is the resistance in ohms, C is the capacitance in farads, $$E(t)$$ is the electromotive force in volts, $$q(t)$$ is the charge in coulombs on the capacitor at time $$t, ext { and } I=d q / d t$$ is the current in amperes. Find the current at time t if the charge on the capacitor is initially zero, the initial current is zero, $$L=10 mathrm{H}, R=20 Omega, C=(6260)^{-1} mathrm{F}$$ and $$E(t)=100 mathrm{V}$$ [Hint: Differentiate both sides of the differential equation in (20) to obtain a homogeneous linear second-order equation for $$I(t)$$ Then use (20) to determine $$d I / d t ext { at } t=0.$$