i) A lens maker wants to craft a biconvex lens out of quartz glass which will encompass a focal length of 20cm. By using the lens maker's formula and supposing both sides of the lens are symmetric, find out the radius of curvature that each surface needs in order to generate the desired focal length.
ii) An object 4cm tall is positioned 10cm from the thin converging lens manufactured in Part (i). Compute the position and size of the image of the object and find out its nature.