Answers to practice exam #2 ---------------------------- 1) the potential difference between the plates is halved 2) increases the potential difference between the plates 3) (many answers possible) 4) (many answers possible) 5) 4 microfarads 6) 200 J 7) 1.12 x 10^22 8) 3 9) half that in B 10) change the kinetic energy of a charge Partial Credit -------------- p7 a,b,c) 5.4A left 5.4V 1.2A right 2.4V 2.2A up 6.6V 2.2A up 6.6V 2.2A up 6.6V d) 2.88 W p8 a) R25 = 576 ohms; R150 = 96 ohms b) P25 = 25 W; P150 = 150 W; the 150W bulb burns brighter c) P25 = 18.4 W; P150 = 3.06 W; the 25W bulb burns brighter d) P25 = 576 W; P150 = 96 W; the 25W bulb burns brighter p9 a) 0.33 pF b) 0.42 pF c) 670 microfarads d) 9 billion meters (15 times the radius of the Sun) p10 5/6 of an ohm