a=重-9e.95j (2.6.2) mmm Suppose the particle is at rest (vo=0)when it is first released from the positive plate. The final speed v of the particle as it strikes the negative plate is v,=2la,ly=1 (2.6.3) m where y is the distance between the two plates.The kinetic energy of the particle when it strikes the plate is K=m=95,y (2.6.4) 21 2.7 Electric Dipole An electric dipole consists of two equal but opposite charges,+q and -g,separated by a distance 2a,as shown in Figure 2.7.1. P(xy.0) Figure 2.7.1 Electric dipole The dipole moment vector p which points from-g to +g (in the +y-direction)is given by p=2gaj (2.7.1) The magnitude of the electric dipole is p=2ga,where g>0.For an overall charge- neutral system having N charges,the electric dipole vector p is defined as (2.7.2) 2-11ˆ e y q qE m m m = = = − F E a j G G G (2.6.2) Suppose the particle is at rest ( 0 v = 0 ) when it is first released from the positive plate. The final speed v of the particle as it strikes the negative plate is 2 2 | | y y y yqE v a y m = = (2.6.3) where is the distance between the two plates. The kinetic energy of the particle when it strikes the plate is y 1 2 2 K m y y = v = qE y (2.6.4) 2.7 Electric Dipole An electric dipole consists of two equal but opposite charges, +q and , separated by a distance , as shown in Figure 2.7.1. −q 2a Figure 2.7.1 Electric dipole The dipole moment vector p which points from G −q to +q (in the + y - direction) is given by ˆ p = 2qa j G (2.7.1) The magnitude of the electric dipole is p = 2qa , where . For an overall charge￾neutral system having N charges, the electric dipole vector q > 0 p G is defined as 1 i N i i q = = p ≡ ∑ i r G G (2.7.2) 2-11