Two identical glass(Ng=3/2) equiconvex lenses of focal length f are kept in contact. Thr space between the two lenses is filled with water (Nw=4/3). The focal length of the combination is. A)F B)f/2 C)4f/3 D)3f/4

Dear Student,let the rdius of curvature for both the lens is R1f=32-12Rf=Rnow the water lens is the concave lens os radius Rlets its focal length be f'1f'=43-1-2Rf'=-3R2=-3f2focal lenghtth of the combination is f''1f''=2f+1f'=2f-23f=43ff''=3f4option DRegards

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