A parallel of white light falls on a concave lens , Image of blue , red and green light are formed on other side of the lens at distance x, y and z respectively from the pole of the lens. Then :

A parallel beam of white light falls on a convex lens. Images of blue, yellow and red light are formed on other side of the lens at a distance 20 cm, 20.5 cm and 21.4 cm respectively. The dispersive power of the material of the lens will be

A parallel beam of white light falls on a convex lens. Images of blue, yellow and red light are formed on other side of the lens at a distance of 0.20 m, 0.205 m and 0.214 m respectively. The dispersive power of the material of the lens will be

A parallel beam of white light falls on a convex lens. Images of blue, yellow and red light are formed on other side of the lens at a distance of 0.20m, 0.205m and 0.214m respectively. The dispersive power of the material of the lens will be

A parallel beam of white ligth falls on a convex lens .Images of blue ,yellow nd red ligth are formed on the other side of the lens at distnaces 20 cm,20.5 cm and 21.4 cm respectively.The dispersive power of the material of the lens is