Refraction

Definition and Explanation of Refraction

• Refraction is the redirection of a wave as it passes from one medium to another.
• It can be caused by a change in the wave's speed or a change in the medium.
• Light is the most commonly observed phenomenon of refraction.
• Other waves, such as sound waves and water waves, also experience refraction.
• Refraction occurs when a wave moves into a slower medium.
• The wavefronts get compressed, causing the wave to change direction.
• Light slows down in a medium due to the interaction of its electromagnetic waves with charged particles.
• When light enters a slower medium at an angle, one side of the wavefront is slowed before the other, resulting in a change in angle of travel.
• When light leaves the medium and returns to a vacuum, its speed returns to normal.

Role of Refraction in Optics

• Optical prisms and lenses use refraction to redirect light.
• The human eye also relies on refraction to focus light onto the retina.
• The refractive index of materials varies with the wavelength of light.
• This variation in refractive index causes dispersion, leading to the separation of white light into its constituent colors.
• Instruments like glasses, cameras, binoculars, and microscopes are based on the principles of refraction.

Apparent Depth and Height

• Rays of light from underwater objects appear to bend as they move from water to air.
• The eye traces these rays back as straight lines, causing objects to appear higher or shallower than they actually are.
• This phenomenon is known as apparent depth.
• It affects activities like spearfishing and archery.
• The ratio of apparent to real depth depends on the refractive indexes of air and water.

Dispersion

• Refraction can cause the splitting of white light into a rainbow-spectrum when passing through a glass prism.
• Different colors of light bend at different angles due to varying refractive indexes.
• This phenomenon is known as dispersion.
• It is responsible for rainbows and the colors we see in everyday life.
• Dispersion can be observed when light passes from air to a material with a varying refractive index.

Atmospheric Refraction

• Refractive index of air varies with temperature and pressure.
• Lower pressure at higher altitudes causes light rays to refract towards the Earth's surface.
• This phenomenon is known as atmospheric refraction.
• It affects the apparent positions of stars near the horizon and the visibility of the sun during sunrise.
• Temperature variations in the air can also cause refraction, leading to effects like heat haze and mirages.

Refraction Data Sources