$A$ plano-convex lens of refractive index ${\mu _1}$ and focal length $f_1$ is kept in contact with another plano-concave lens of refractive index ${\mu _2}$ and focal length $f_2$. If the radius of curvature of their spherical faces is $R$ each and $f_1 = 2f_2$,then ${\mu _1}$ and ${\mu _2}$ are related as:

  • A
    ${\mu _1} + 2{\mu _2} = 3$
  • B
    $2{\mu _1} + {\mu _2} = 1$
  • C
    $3{\mu _2} + {\mu _1} = 1$
  • D
    $2{\mu _2} + {\mu _1} = 1$

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