The critical angle for diamond (refractive index $= 2$) is........$^o$

The phenomenon of total internal reflection is observed when the angle of incidence is

The phenomenon involved in the reflection of radio waves by the ionosphere is similar to:

Light travels in two media $A$ and $B$ with speeds $1.8 \times 10^8 \ m/s$ and $2.4 \times 10^8 \ m/s$ respectively. Then the critical angle between them is

$A$ well-cut diamond appears bright because

$A$ beam of light consisting of red,green and blue colours is incident on a right-angled prism. The refractive index of the material of the prism for the above red,green and blue wavelengths are $1.39, 1.44$ and $1.47$ respectively.
The prism will