If two structure of same cross-sectional area

PHYSICS · Single correct · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments

Problem

If two structure of same cross-sectional area, but different numerical apertures

NA_1

and

NA_2

(

NA_2 < NA_1

) are joined longitudinally, the numerical aperture of the combined structure is (1)

\frac{NA_1 NA_2}{NA_1 + NA_2}

(2)

NA_1 + NA_2

(3)

NA_1

(4)

NA_2