Q.No.12.4: - Describe the force or forces on a positive point charge when placed between parallel plates. (a) with similar and equal charges. (b) with opposite and equal charges.

Q.No.12.4: - Describe the force or forces on a positive point charge when placed between parallel plates.

(a)    with similar and equal charges.

(b)    with opposite and equal charges.

Ans: - (a). If the plates have similar and equal charge in magnitude and we place the positive point charge between such plates then both the plates want to repel this positive point charge with same Coulomb’s force. The net force on the charge will be zero.

          (b). If the plates have similar and opposite charge in magnitude and we place the positive point charge between such plates then positive plate will repel the positive charge and exert a force F₁ while negative plate will attract it and exert an attractive force F₂.

          Net force        =           F        =      F₁   +     F₂