9. An electric dipole in a uniform horizontal electric field of magnitude 2.5 x 105 N/C is currently at rest and makes an angle 0 = 17° with the E field. The charges have equal magnitudes q = 3.0 µC and are separated by a fixed distance 2a = 2.0 x 10-8 m. When released, the dipole swings clockwise about an axis through its center, with no friction or other damping, until it next comes to rest. At that moment, what angle will the dipole make with the E field? 2a a) 11° b) 14° c) 17° d) 21° e) 24°

Two equal charges are situated on the x axis at 40.0 cm on either side of the origin as shown in the figure below. Location A is on the perpendicular bisector at a distance of 21.0 cm from the origin on the y axis. (Assume that the +x axis is directed to the right and they axis is directed up.) 91 *A 92 (a) If q,- -3.50 C and q,- -3.50 C what is the net electric field due to both charges at location A? Express your answer in vector form. 1.64-10%) x Did you consider the symmetry of the situation? What is the net contribution to the field from the x components of the field from each charge? N/C (b) If a, 3a, (where q,- -3.50 pC), what is the net electric field at location A due to both charges? Express your answer in vector form -4.68-10%-4.1-10% x If the two charges are unequal, what is the net contribution to the field from each charge in the two perpendicular directions? N/C

-A ZE The potential difference between the accelerating plates of a TV set is about 30 kV. If the distance between the plates is 1.3 cm, find the magnitude of the uniform electric field in the region between the plates. N/C

2. Charged particle interactions and energy conservation A stationary charge, Q = + 31.0uC, remains fixed in position. A moving charge, q = + 7.70µC, with mass, m = 1.18 x 10 kg, heads toward this stationary charge along the x axis. The moving charge starts at position A with an initial speed of 892 m/s. Point A is 1.64 m from the fixed charge. Point B is 0.550 m from the fixed charge. a. Use energy conservation principles to set up an energy conservation equation for this system. b. Solve the energy conservation equation for the speed of the moving charge, vx, when it reaches point B. q. m >+ x axis Fixed stationary charge