Two long straight parallel lines,#1 and #2,carry uniform positive linear charge densities.The charge density on line #2 is twice as great as the charge density on line #1.The locus of points where the electric field due to these lines is zero is
A) along a line between the lines closer to line #2 than line #1.
B) at a point midway between the lines.
C) along a line perpendicular to lines #1 and #2.
D) along a line between the lines closer to line #1 than line #2.

Question

Quizplus · Accepted Answer

The electric field is zero at a point where the electric fields due to both lines cancel each other out. Since line #2 has a greater charge density, the point where the electric fields cancel out must be closer to line #1, as the electric field strength is inversely proportional to the distance from the charge source.

Two Long Straight Parallel Lines,#1 and #2,carry Uniform Positive Linear