A plastic solid sphere is positively charged with volume charge density +p. The sphere has a radius a and centered at origin. Another empty sphere with radius b is placed at 2b cm away from the origin on y-axis. The small sphere has no charge in it. Find the electric field (E =?) at point P by using the Gaussian method (a > 3b, c > a).

A plastic solid sphere is positively charged with volume charge density +p. The sphere has a radius a and centered at origin. Another empty sphere with radius b is placed at 2b cm away from the origin on y-axis. The small sphere has no charge in it. Find the electric field (E =?) at point P by using the Gaussian method (a > 3b, c > a).