6.3.2 Refraction of Waves

• Refraction is the bending of waves as they pass from one medium to another due to a change in their speed.
• Refraction occurs because waves change their speed as they move from one medium to another.
• The refractive index of a medium is a measure of how much the speed of light is reduced when passing through that medium.
• Light travels fastest in a vacuum.
• Snell's Law relates the angles of incidence and refraction using the refractive indices of the two media.
• What is the refractive index of water?

  1.33
• Snell's Law is mathematically expressed as $n_{1} \sin \theta_{1} =$$n_{2} \sin \theta_{2}$


  True
• When light passes from air into water, does the angle of refraction increase or decrease compared to the angle of incidence?

  Decrease
• Refraction occurs because waves change direction due to a change in speed


  True
• Arrange the steps of what happens when light passes from air into water:

  1️⃣ Light enters water

  2️⃣ Light slows down

  3️⃣ Light bends towards the normal
• Refraction occurs because waves change speed due to a difference in medium density
• What direction does light bend when it travels from a low-density medium to a high-density medium?

  Towards the normal
• The refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium


  True
• The formula for refractive index is $n =$$\frac{c}{v}$, where c is the speed of light in a vacuum
• What is the critical condition for total internal reflection to occur?

  Angle of incidence > critical angle
• $\theta_{2}$ is the angle of refraction.
• What is the refractive index of air?

  1.0003
• The refractive index of water is 1.33.
• What devices use Snell's Law to refract light?

  Lenses and prisms
• Total internal reflection occurs when light strikes a boundary from a denser to a less dense medium at an angle greater than the critical angle.
• What are two applications of total internal reflection?

  Fiber optic cables and prisms
• How do prisms use total internal reflection?

  To create a clear image
• Total internal reflection occurs when light travels from a medium with a higher refractive index to a medium with a lower refractive index.
• Total internal reflection occurs when the angle of incidence is greater than the critical angle


  True
• What happens to the angle of refraction at the critical angle?

  It becomes 90 degrees
• Total internal reflection is used in optical fibers, prisms, and the working of diamonds.
• What is the Bent Straw Effect an example of?

  Refraction
• What phenomenon creates a rainbow?

  Refraction
• Light passing from air into water slows down and bends towards the normal.

  True
• Match the medium with its refraction direction when light enters from air:

  Air ↔️ Away from Normal

  Water ↔️ Towards Normal
• The speed of light in a vacuum is approximately 3 x 10^8 m/s.


  True
• Light bends more when it enters a medium with a higher refractive index.


  True
• Snell's Law is expressed as n₁sin θ₁ = n₂sin θ₂.

  True
• Snell's Law describes the relationship between the angles of incidence and refraction
• Match the variables in Snell's Law with their meanings:

  $n_{1}$ ↔️ Refractive index of medium 1

  $\theta_{1}$ ↔️ Angle of incidence

  $\theta_{2}$ ↔️ Angle of refraction
• Snell's Law is used in optical devices like lenses and prisms
• Light travels faster in a medium with a higher refractive index

  False
• Snell's Law is mathematically expressed as $n_{1} \sin \theta_{1} =$$n_{2} \sin \theta_{2}$, where $\theta_{2}$ is the angle of refraction
• Fiber optic cables use total internal reflection to transmit data

  True
• What is $\theta_{1}$ referred to in refraction?


  Angle of incidence