Refraction

When an object is viewed through a glass slab, it appears raised due to the refraction of light. The formula to calculate the refractive index of the glass is: Here, - is the real thickness of the glass slab - is the vertical shift (apparent reduction in thickness due to refraction).

The correct option is (B):

The air above a fire is hotter and less dense compared to the surrounding cooler air. This causes the light rays coming from objects behind the fire to bend as they pass through air layers of different densities. This bending of light is called refraction, and it makes the objects appear to sway or shimmer. So, the swaying appearance of objects is due to the refraction of light.

The correct answer is option (A) : refraction

The critical angle is given by the formula: Here, (glass), (air), so

The correct answer is option (A):

The refractive index of a material indicates how much it can bend light. A higher refractive index means greater bending of light.
Among the given options:
- Refractive index of diamond ≈ 2.42
- Refractive index of kerosene ≈ 1.44
- Refractive index of Canada balsam ≈ 1.55
- Refractive index of air ≈ 1.0003

Hence, diamond has the highest refractive index.

The correct answer is option (A): Diamond

The twinkling of stars is due to the atmospheric refraction of light. As light from a star passes through the Earth's atmosphere, it encounters layers of air with varying temperatures and densities. These layers act like prisms, bending (refracting) the light. Since the atmosphere is constantly changing, the amount of bending varies continuously. This causes the star's apparent position and brightness to fluctuate, making it appear to twinkle.

Reflection is the bouncing back of light from a surface.
Total internal reflection occurs when light travels from a denser medium to a rarer medium at an angle of incidence greater than the critical angle. Dispersion is the splitting of white light into its constituent colors.