試題詳解

17. In a certain region, the electric potential due to a charge distribution is given by the equation V(x.y) = 2xy - x² - y, where x and y are measured in meters and V is in volts. At which point is the electric field equal to zero?
(A) x=0.5 m,y=0.5 m
(B) x=0m,y=0m
(C) x=1m,y=1m
(D) x=0.5 m,y=1 m
(E) x=1m,y=0.5m