Ramu has been given a tub of water with a refractive index of 1.33, a mug of oil with a refractive index of 1.46, a bottle of glycerine with a refractive index of 1.5 and a glass-slab with a refractive index of 1.65. Light will travel fastest in:

The correct answer is water.

Key Points

• Light travels fastest in a medium with the lowest refractive index.
• Water has the lowest refractive index (1.33) among the given options.
• A lower refractive index indicates that the medium is less optically dense, allowing light to travel through it more quickly.
• Compared to oil (1.46), glycerine (1.5), and glass-slab (1.65), water provides the least resistance to the propagation of light.

Additional Information

• Refractive Index
  • The refractive index of a material is a measure of how much the speed of light is reduced inside the medium compared to the speed of light in a vacuum.
  • The formula for refractive index (n) is n = c/v, where c is the speed of light in a vacuum and v is the speed of light in the medium.
• Speed of Light in Different Media
  • The speed of light in a vacuum is approximately 299,792 km/s.
  • In materials with higher refractive indices, the speed of light is slower.
• Optical Density
  • Optical density refers to how much a material can slow down light. Materials with higher refractive indices are optically denser.
  • Water, being less optically dense compared to oil, glycerine, and glass, allows light to travel faster through it.
• Applications
  • Understanding the refractive index is crucial in designing lenses, optical instruments, and various scientific applications.
  • It helps in determining how light will behave when transitioning between different media.