The refractive index of a converging lens is \( 1.4 \). What will be the focal length of this lens if it is placed in a medium of same refractive index? Assume the radii of curvature of the faces of lens are \( R_{1} \) and \( R_{2} \) respectively.
\( 1 \)
Infinite
Zero
\( \dfrac{R_{1} R_{2}}{R_{1} - R_{2}} \)
