Refraction

• Refraction happens when light enters a new medium at an angle:

  • One side of the light wave enters the new medium first
  • This side slows down before the other side
  • Causes the light to change direction or bend

  Imagine a marching band:

  • When part of the band hits soft ground first
  • Those soldiers slow down
  • The whole band's direction changes
  • Light does something similar when entering a new material

  This bending depends on:

  • Angle of entry
  • Density difference between materials
• Light speed varies depending on the material it travels through:

  • In vacuum: Fastest speed ($3 \times 10^8$m/s)
  • In air: Slightly slower
  • In water: Much slower
  • In glass: Even slower
• Refraction is the bending of light when it passes from one transparent medium to another at an angle.

  Imagine light as a group of travelers:

  • When they enter a new country (medium) with different rules (density)
  • They change their path slightly
  • They don't move in the same straight line anymore

  Key points about refraction:

  • Occurs when light passes between different media (like air to water)
  • Happens because light changes speed in different materials
  • Causes light to change direction
• Light is a form of electromagnetic radiation that travels in waves. It typically moves in straight lines through a uniform medium at a constant speed.

  Key characteristics:

  • Travels at approximately$3 \times 10^8$meters per second in a vacuum
  • Can be reflected, refracted, or absorbed
  • Behaves both as a wave and a particle (wave-particle duality)
• Imagine light as a team of runners crossing from a hard floor to a soft carpet:

  • When the team enters the carpet at an angle
  • The first runners slow down
  • But the other runners are still moving at the original speed
  • This makes the whole team change direction

  In light terms:

  • When light hits a new material at an angle
  • Part of the light slows down first
  • This makes the entire light beam bend
  • The more different the materials, the more dramatic the bend
• The two key factors that determine how much a light beam will bend when entering a new material are:

  1. The angle at which the light hits the new material
  2. The difference in density between the two materials

  The greater the angle of entry and the larger the density difference, the more the light will bend or refract. Excellent understanding of what causes the bending of light!
• Refraction happens all around us:

  1. Water examples:

  • Straw in a glass of water looks bent
  • Fish appear closer to the surface than they really are
  • Rainbows form through water droplets

  1. Optical examples:

  • Eyeglasses correct vision through lens refraction
  • Telescopes and microscopes use refraction
  • Prisms split white light into colors
• The reason a straw in a glass of water appears bent is due to the refraction of light. When light travels from the air into the water, it changes speed and direction, creating an optical illusion that makes the straw look bent or broken. This is a classic example of how refraction can alter our perception of objects in the real world.