Correct Answer - B
b. Let us complete the sphere. Electric field due to lower part at
A is equal to electric field due to upper part at B = E (given)
Electric field due to lower
part at B = electric field due
to full sphere - electric field
due to upper part
` = (kQ)/(2R)^2 - E`
` = 1/(4piepsilon_0) (rho(4//3)piR^3)/(4R^2) - E`
`= (rhoR)/(12epsilon_0) - E`