Abeam of light is traveling inside a solid glass cube having index of refraction 1.53. it strikes the surface of the cube from the inside. (a) if the cube is in air, at what minimum angle with the normal inside the glass will this light not enter the air at this surface? (b) what would be the minimum angle in part (a) if the cube were immersed in water?

object 2 because all the other ones are wrong

see earlier

gas and liquid

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.