Five charges, q each are placed at the corners of a regular pentagon of side ‘a’ as shown.
(i) What will be the electric field at O if the charge from one of the corners (say A) is removed?
(ii) What will be the electric field at O if the charge q at A is replaced by –q?
(i)The point O, the center of the pentagon is equidistant from all the charges at the end point of pentagon. Thus, due to symmetry, the electric field due to all the charges are cancelled out. As a result, electric field at O is zero.
(ii) We can write that the vector sum of electric field due to charge A and electric field due to other four charges at the center of cube should be zero
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