Question

Light is travelling from glass to air. Its speed in glass is 2.0 x10 m/s. Find the critical angle of glass-air boundary. ( Use n air=1, c= 3 × 10®8 m/s)

a= 41.8°
b=45.7°
c=60°​

Answer 1

know that refractive index n=

speedoflightinmedium

speedoflightinvacuum

where c=3×10

8

m/s

1.5=

v

c

v=

1.5

3×10

8

v=2×10

8

m/s

For critical angle we will use snell's law

C is critical angle

n

glass

sinC=n

air

sin90 n

air

=1

sinC=

n

glass

1

=

1.5

1

C=60 degree

o