Recall that for a finite rod of length L and total charge Q, the electric field for a point located a perpendicular distance r from the middle of the rod has a magnitude given by:

Consider the limit of large distances, where a finite charged rod is observed at a distance that is very large when compared to the length of the rod.

In this situation, the electric field best resembled that of a ...


a)point charge ... it goes like r-2

b) infinite line ... it goes like r-1

c) electric dipole ... it goes like r-3

d) infinite plane ... it is constant

none of the above ... it is zero

1 answer

The finite rod of length L and charge Q looks more like a point source as the observer gets farther way.

The answer is a)