3.9 Refraction at a plane surface

• The formula for Snell's Law is $\frac{\sin \theta_{i}}{\sin \theta_{r}} =$$\frac{n_{2}}{n_{1}}$
• When light travels from a medium with a lower refractive index to a higher refractive index, it bends towards
• What does the variable $\theta_{i}$ represent?


  Angle of incidence
• What is the formula for calculating the angle of refraction ($\theta_{r}$)?


  $\theta_{r} =$$\sin^{ - 1}\left(\frac{n_{1}}{n_{2}}\sin \theta_{i}\right)$
• What does the variable $n_{2}$ represent?


  Refractive index of second medium
• Snell's Law relates the angles of incidence and refraction to the refractive indices of the two media.
• If light enters a denser medium, it bends towards the normal.
• What does \theta_{i}</latex> represent?

  Angle of incidence
• Light bends towards the normal when it passes from air into water.


  True
• What does a higher refractive index indicate?

  Greater bending of light
• Match the variable with its description:

  $\theta_{i1}$ ↔️ Angle of incidence at the first interface

  $\theta_{r2}$ ↔️ Angle of refraction at the second interface
• Refraction is the change in direction of a wave as it passes from one medium to another due to a change in wave speed
• Match the variable with its description:

  n_{1}</latex> ↔️ Refractive index of the first medium

  $\theta_{i}$ ↔️ Angle of incidence

  $n_{2}$ ↔️ Refractive index of the second medium

  $\theta_{r}$ ↔️ Angle of refraction
• Steps to calculate the angle of refraction using Snell's Law:

  1️⃣ Rearrange Snell's Law to solve for $\theta_{r}$

  2️⃣ Substitute the values of $n_{1}$, $n_{2}$, and $\theta_{i}$

  3️⃣ Calculate the value of $\sin \theta_{r}$

  4️⃣ Find the inverse sine of $\sin \theta_{r}$ to get $\theta_{r}$
• The variable $\theta_{r}$ represents the angle of refraction.
• What is the mathematical expression for Snell's Law?

  \frac{\sin \theta_{i}}{\sin \theta_{r}} = \frac{n_{2}}{n_{1}}</latex>
• When light travels from air into water at an angle of incidence of 30°, the angle of refraction is approximately 22.1°.

  True
• What is the mathematical expression for Snell's Law?

  \frac{\sin \theta_{i}}{\sin \theta_{r}} = \frac{n_{2}}{n_{1}}</latex>
• If light enters a less dense medium, it bends away from the normal.


  True
• The angle of refraction can be calculated using the formula $\theta_{r} =$$\sin^{ - 1}\left(\frac{n_{1}}{n_{2}}\sin \theta_{i}\right)$.


  True
• The refractive index $n$ is defined as the ratio of the speed of light in vacuum to its speed in the medium
• When light exits a rectangular prism into air, it bends away from the normal
• What phenomenon is described by Snell's Law in optical fibers?

  Refraction
• Snell's Law relates the angles of incidence and refraction to the refractive indices of the media.


  True
• If light travels from a medium with a lower refractive index to a higher one, it bends towards the normal.


  True
• The formula to calculate $\theta_{r}$ is $\theta_{r} =$$\sin^{ - 1}\left(\frac{n_{1}}{n_{2}}\sin \theta_{i}\right)$.


  True
• Snell's Law can be used to calculate the angle of refraction given the angle of incidence and refractive indices.


  True
• The variable $n_{1}$ represents the refractive index of the first medium.
• What is refraction?

  Change in wave direction
• What does the refractive index measure?

  How much light slows down
• What does $n_{1}$ represent?


  Refractive index of first medium
• What is the angle of refraction when light travels from air (n = 1.0) into water (n = 1.33) at an angle of incidence of 30°?

  22.1°
• Match the medium with its refractive index:

  Vacuum ↔️ 1.000

  Water ↔️ 1.33

  Air ↔️ 1.0003

  Glass ↔️ 1.50-1.75
• What is the overall effect of light passing through a rectangular prism with parallel sides?

  Changes direction but not position