C11.8 Refractive Index

Refraction

The bending of a wave as it passes from one medium to another due to a change in speed.

Refractive index (n)

A property of a material that indicates how much the speed of light is reduced in that material compared to a vacuum.

Snell's Law

n1sin(θ1) = n2sin(θ2), used to describe the relationship between the angles of incidence and refraction when light passes between two media.

Equation for refractive index (n)

n = c/v, where c is the speed of light in vacuum and v is the speed of light in the medium. n will always be greater than or equal o 1, as v can never be greater than c.

Value of n in a vacuum

1, since light travels at its maximum speed.

Value of n in water

1.33, indicating light travels slower in water than in a vacuum.

Value of n in crown glass

1.52, showing a greater reduction in light speed compared to water.

Value of n in diamond

2.42, indicating significant slowing of light.

Effect of higher refractive index

The greater the refractive index (n), the greater the change in speed of light and the greater the refraction towards the normal.

Frequency of a wave during refraction

Frequency remains the same when a wave refracts.

Wavelength change during refraction

Wavelength changes when a wave enters a different medium.

Refraction direction in denser media

When light enters a denser medium, it refracts towards the normal.

Refraction direction in less dense media

When light enters a less dense medium, it refracts away from the normal.