Physics · 2018
JEE Main · 15 April 2018, Shift 1 · Q22
A planoconvex lens becomes an optical system of 28 cm focal length when its plane surface is silvered and illuminated from left to right as shown in…
A planoconvex lens becomes an optical system of $\displaystyle 28$ cm focal length when its plane surface is silvered and illuminated from left to right as shown in Fig-A.
If the same lens is instead silvered on the curved surface and illuminated from other side as in Fig.B, it acts like an optical system of focal length $\displaystyle 10$ cm. The refractive index of the material of lens is :
Official answer
(2)
$\displaystyle 1.55$
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JEE Main 2018 Physics question, with the answer from NTA’s final answer key. Where our answers come from.