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:
a. μ1+μ2=3
b. 2μ1−μ2=1
c. 3μ2−2μ1=1
d. 2μ2−μ1=1