A plano convex lens of refractive index µ1 and focal length f1 is kept in contact with another plano concave lens of refractive index µ2 and focal length f2 . If the radius of curvature of their spherical faces is R each and f1 = 2f2 , then µ1 and µ2 are related as :
(1) 3µ2 - 2µ1 = 1
(2) 2µ2 - 2µ1 = 1
(3) 2µ1 - 2µ2 = 1
(4) µ1 + µ2 = 3