Divergence & Poisson’s & Laplace’s Equation 

Same query .if a test charge is on upper side why we had taken 2 * D.ds in infinite sheet?

@@chetansinghnegi2416 In the last lecture he took up the problem of infinite surface charge distribution. In that configuration the surface element is along -z(hat) direction and also field in the bottom surface was along -z(hat) direction ,so in the Gauss's law equation the these two negative sign cancelled off each other

In this problem you don't have any information of D field as you had earlier so the sign of-x(hat) reflected here

chirag gurung watch every lecture in detail if you want to understand EMT.

chirag gurung it would be more easy then to understand segregated lectures or topics.

@@shivaniits have you understood EMT fully after this course ?