Thu June 21, 2012 By: Arvindh Jambunathan

Q.. A charge of 17.7 x 10 -4 C is distributed uniformly over a large sheet of area 200 m2. Calculate the electric field intensity at a distance 20 cm from it in air.

Expert Reply
Thu June 21, 2012
In this case the size of the sheet is too large as compared to the distance from it so we can consider the sheet to be infinite in size.
Thus the charge density would be s= (17.7 x 10-4 /200) C/m2
so the Electric field will be: s/2?
However, if you dont want to consider the infinite sheet assumption you will have to know the exact geometry of the sheet. Then we will have to use double area integral considering charge at a very small differential area as point charges and then integrating it using the exact geometry, but is quite cumbersome.
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