Question

Prof. Parchure
Prof. Avinash
PHYSICS PRIVATE TUITIONS - XI
23. Two transparent slabs are of equal thickness, one is made of material A of refractive index
1.5 and the other is made of two materials B and C the ratio of their thickness being 1 : 2.
The refractive index of C is 1.6 .If monochromatic parallel beams passing through the slabs
have the same number of waves, the refractive index of B is -
a) 1.4
A
- 1.3
b) 1.3
c) 1.1
B
C
-1.6
d) 1.5​

Answer 1

Answer:

Given: n

A

=1.5; n

C

=1.6

Optical path length traveled by beam is same in both the slabs.

∴ n

A

t=n

B

×

3

t

+n

C

×

3

2t

∴ (1.5)t=n

B

×

3

t

+(1.6)×

3

2t

⟹n

B

=1.3