A cubical transparent slab is used as a paper weight. What should be the minimum refractive index of the material of the slab so that letters below it
A cubical transparent slab is used as a paper weight. What should be the minimum refractive index of the material of the slab so that letters below it are not visible from any of its vertical faces.
A. `sqrt(2)`
B. `sqrt(3)`
C. `sqrt(5)`
D. `sqrt(5)//sqrt(3)`
5 views