3. An infinite and grounded conducting plane sits on the xy plane at z = 0. Above the plane, positive charges q₁ and q2 are placed on the z axis at positions z = a and z = b respectively, with a < b. Using the method of images, find the induced charge density on the conducting plane at radius P from the origin.

3. An infinite and grounded conducting plane sits on the xy plane at z = 0. Above the plane, positive charges q₁ and q2 are placed on the z axis at positions z = a and z = b respectively, with a < b. Using the method of images, find the induced charge density on the conducting plane at radius P from the origin.