Question

A point object 'O' is placed in a medium of
refractive index n= 1.4. S1 and S2 are
two concentric spherical surfaces of radii
1m and 2m. To the right of ‘O'contains a
medium of refractive index n = 1.5
between the interfaces S, and S . Find the
object distance of O from S, (in meter) so
that an image of 'O' as seen by observer
from air, coincides with O.​

Answer 1

Answer:

PHYSICS

(a) A point object 'O' is kept in a medium of refractive index n in front of a convex spherical surface of radius of curvature R which separate the second medium of refractive index n2from the first one as shown in the figure.

Draw the ray diagram showing the image formation and deduce the relationship between the object distance and the image distance in terms of n1,n2 and R.

(b) When the image formed above acts as a virtual object for a concave spherical surface separating the medium n2 and n1(n2>n1) draw this ray diagram and write the similar (similar to (a)) relation. Hence obtain the expression for the lens maker's formula

October 15, 2019Sultan Kamala

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VIDEO EXPLANATION

ANSWER

(a)

tan∠NOM=OMMN

tan∠NCM=MCMN

tan∠NMI=NIMN

For △NOC,i is the exterior angle.

i=∠NOM+∠NCM 

  =OMMN+MCMN

Similarly, 

r=MCMN−MIMN

By Snell's Law,

n1sini=n2sinr

For small angles,

n1i=n2r

n1(OMMN+MC