The video explains how light travels at different speeds in various mediums, such as air and water, due to differences in density. It introduces the concept of refraction, where light changes speed and direction when moving between mediums. This phenomenon is demonstrated with a laser and a tank of water. The video also discusses how refraction occurs in the human eye, focusing light on the retina. It explains vision issues like nearsightedness and farsightedness and how lenses can correct these by altering the path of light to focus correctly on the retina.

What happens to light when it passes from air into water?

• It stops completely.

• It slows down and changes direction.

• It speeds up and continues in the same direction.

• It speeds up and changes direction.

What is the term used to describe the bending of light at the boundary between two different mediums?

• Dispersion

• Diffraction

• Reflection

• Refraction

How does the cornea help in focusing light in the human eye?

• It bends light to focus it on the retina.

• It absorbs light to prevent glare.

• It diffuses light to reduce intensity.

• It reflects light away from the retina.

Which type of lens is used to correct nearsightedness?

• Convex lens

• Cylindrical lens

• Bifocal lens

• Concave lens

What effect does a convex lens have on light for someone who is farsighted?

• It scatters the light, making the image clearer.

• It converges the light, shortening the focus distance.

• It diverges the light, increasing the focus distance.

• It reflects the light, preventing it from reaching the retina.