Question

7 A ray of light is incident normally on a glass slab of thickress 4 cm and R.I. 1.5. The time taken by the ray to travel from source to surface of slab is same as to travel through glass slab. Calculate the distance of source from the surface.​

Answer 1

Answer:

Correct option is B)

Let, T

1

=time taken to reach from source to surface

T

2

=time taken to travel through glass slab

Speed in glass v=

μ

c

where μ=1.6

Now S

1

=distance of source from the surface

and S

2

=thickness of slab=distance traveled in slab

T

1

=T

2

⟹

c

S

1

=

v

S

2

=

c

S

2

μ

⟹S1 =1.6×5cm

⟹S 1 =8cm