The video tutorial explains the concept of refraction, which occurs when light bends due to a change in velocity at the boundary between two media. It introduces optical density as a measure of how much a medium slows light, affecting its refractive index. The tutorial illustrates refraction from low to high optical density, such as air to water, and from high to low density, like water to air, using a coin experiment. This experiment shows how light bends away from the normal, allowing the viewer to see the coin when water is added.

What is the term used to describe how much a medium slows down the transmission of light?

• Medium transparency

• Refractive index

• Optical density

• Light velocity

What is the effect of optical density on the speed of light in a medium?

• Higher optical density increases light speed

• Higher optical density decreases light speed

• Optical density has no effect on light speed

• Optical density only affects light color

When light travels from a medium of higher optical density to one of lower optical density, how does it refract?

• Towards the normal

• Away from the normal

• In a straight line

• It does not refract

In the example with the coin and water, why does the coin become visible when water is added?

• The water magnifies the coin

• The water reflects the light

• The light bends towards the normal

• The light bends away from the normal

What happens to the angle of refraction when light moves from water to air?

• It remains the same

• It decreases

• It becomes zero

• It increases