Question

A ray of light passing through an equiangular glass prism at a minimum deviation. i) What are the two conditions it holds good?

Answer 1

Answer:

Here, Angle of prism, A=60

o

Angle of incidence, i=

4

3

×60

i+e=A+δ

e is emergence angle

where δ is deviation angle

At minimum deviation δ=δ

min

i=e

2i=A+δ

min

2×45=60+δ

min

δ

min

=30

By prism law,

μ=

sin

2

A

sin

2

A+δ

min

μ=

sin

2

60

sin

2

60+30

=

2

2

=1.41

Let v be velocity of light in prism

v=

μ

c

=

1.41

3×10

8

=2×10

8

m/s