JEE Advanced 2020 Concept Recapitulation Test 4 Paper 2

For first refraction
‌

µ2

V

−‌

µ1

u

=‌

µ2−µ1

R

‌

2

v

−‌

1

α

=‌

2−1

R

⇒v=2R
As 45∘ is greater than critical angle of 30∘ so the rays gets totally reflected at the second face. So the plane surface will behavelike plane mirror.