Figure 2-8 Two t:qual magnitude point charges are a distanct: II apart along the t axis. (a) Wht:n the charg« art: of Ihe samt: polarilY, tht: d«tric fidd dut: to t:ach is radially dir«l~ away. In tht: t '"' 0 symmetry plant:. Iht: nt:1 fidd compont:nl is radial.
(b) When tht: charges are of oppositt: polarity, the dt:ctrk fit:ld dut: 10 tht: nt:gativt: charge is dirt:cted radially inwards. In the z '"" 0 symmetry plane. Ihe nt:t fidd is now -z directt:d.