Q. If the electric field given by $\left( 5\widehat{\mathbf{i}} + 4\widehat{\mathbf{j}} + 9\widehat{\mathbf{k}} \right),$ the electric flux through a surface of area 20 unit lying in the Y-Z plane will be
A) 100 unit
B) 80unit
C) 180 unit
D) 20 unit
Explanation
(a) Electric flux is equal to the product of an area element and the perpendicular component of E. As the surface is lying in Y-Z plane
$\therefore\mathbf{E}.d\mathbf{A} = \phi = (5)(20)$
$= 100\ unit.$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.