For items 18-20, refer to the problem below: A resistance of 2000 ohms and a capacitance of 5 x 10-4 farads are connected in series with an electromotive force of 100 volts. 18. Set up the differential equation necessary to find the charge on the capacitor at any time t. da 1 A + da C. q= + 9 = 20 20 dt da da B. D. + 204 = dt +q = 20 1 1 dt dt 20 19. What is the charge at any time t? Aq(t) = 20(1-et) B. q(t) = z(e-+-1) C. q(t) = x (1 – e-6) D.q(t) = 20(et – 1) 20. Find the current at t = 0.1 sec. A. i 0.15 A B. i 0.05 A C. i 0.35 A D. i 0.25 A