申論題

1.(15%) Consider three fixed point charges are located in a rectangular coordinate sys Q₁= +4 μC is located at (0 cm, 2 cm), charge Q₂ = -3 μC is located at( cm, 1 cm), and charge Q₃ = +5μC is located at (  cm, -1 cm). (The permittivity (ε₀)=(F/m)