A plano convex lens of refractive index μ_1 and focal length f_1 is kept in contact with another plano concave lens of refractive index μ_2 and focal…

A plano convex lens of refractive index $\displaystyle \mu_1$ and focal length $\displaystyle f_1$ is kept in contact with another plano concave lens of refractive index $\displaystyle \mu_2$ and focal length $\displaystyle f_2$. If the radius of curvature of their spherical faces is R each and $\displaystyle f_1=2 f_2$, then $\displaystyle \mu_1$ and $\displaystyle \mu_2$ are related as :