Gausss Law is always true but not always useful For the 12 o

Gauss’s Law is always true but not always useful. For the 12 objects below, circle all and only those objects for which Gauss’s Law will prove useful for finding the electric field strength E in the vicinity of the object.

circular hoop (2D) finite squat cylinder (3D) semi-circular rod (2D) infinite rod (ID) regular polygon (2D) short rod (1D) finite square (2D) finite rectangle (2D) solid regular polygon (2D) solid sphere (3D) solid ellipsoid (3D) solid cube (3D)

Solution

Gauss law will prove useful only in case of infinite rod and Solid sphere.

1. In case of infine rod the electic field direction will always be prepedicular to rod\'s axis. so gauss law will be able to be used by a closed surface in form of cylinder.

2. Electric field direction will always be along to solid sphere surface normal direction. So so gauss law will be able to be used by a closed surface in form of sphere.