4.4.5 Refraction

• What is the effect of a higher refractive index on the speed of light in a medium?

  Decreases the speed
• If light passes from air to water at an incidence angle of 30 degrees, the angle of refraction is approximately 22.1 degrees.
• Match the components of Snell's Law with their meanings:

  n1 ↔️ Refractive index of the first medium

  n2 ↔️ Refractive index of the second medium

  θ1 ↔️ Angle of incidence

  θ2 ↔️ Angle of refraction
• What is the refractive index of a medium defined as?

  Ratio of light speeds
• The speed of light in a medium is always slower than in a vacuum.


  True
• Total internal reflection occurs when the angle of incidence exceeds the critical angle.


  True
• What is refraction defined as?

  Change in wave direction
• What does Snell's Law describe?

  Angles of incidence and refraction
• Light bends towards the normal when entering a denser medium.


  True
• How is the refractive index of a medium defined?

  $n =$$\frac{c}{v}$
• The speed of light in a vacuum is approximately 2.998 \times 10^8 m/s.
• Total internal reflection requires a critical angle to occur.


  True
• What is the angle of incidence in the example where light passes from air to glass?

  45^\circ
• Light passing from air into glass bends towards the normal because the refractive index of glass is greater than air.

  True
• What do the variables \(n_1\) and \(n_2\) represent in Snell's Law?

  Refractive indices
• Convex lenses are used in eyeglasses to correct farsightedness
• An image formed by a convex lens with a focal length of 10 cm is located 15 cm from the lens if the object is 30 cm away.


  True
• Match the optical device with its use of refraction:

  Eyeglasses ↔️ Correct vision problems

  Telescopes ↔️ Focus light from distant objects
• When a wave passes from a lower refractive index to a higher one, it bends towards the normal.


  True
• The refractive index of a medium is defined as the ratio of the speed of light in a vacuum to the speed of light in that medium.
• As the refractive index increases, the speed of light decreases
• When light enters water, why does its speed decrease?

  Higher refractive index
• What happens to light traveling from water to air if the angle of incidence is greater than the critical angle?

  Total internal reflection
• When light passes from a medium with a lower refractive index to a higher refractive index, it bends towards the normal
• Snell's Law is given by the formula: n_1 sin θ_1 = n_2 sin θ_2
• What is Snell's Law used to describe?

  Refraction of light
• As the refractive index increases, the speed of light decreases.


  True
• Why does light slow down when entering water?

  Water has a refractive index
• What are the variables in Snell's Law used to describe?

  Refractive indices and angles
• What is the second step in solving action problems using Snell's Law?

  Determine the angle of incidence
• In the example provided, what is the angle of refraction when light passes from air into glass at an incidence angle of \(45^\circ\)?

  \(28.1^\circ\)
• The first step in solving refraction problems using Snell's Law is to identify the refractive indices of the media.


  True
• How do corrective lenses in eyeglasses improve vision?

  By bending light to focus correctly
• When light passes through a lens, the curved surfaces cause it to refract
• How do prisms use refraction to create a spectrum of light?

  By dispersing white light
• Refraction is the change in direction of a wave when it passes from one medium to another with a different refractive index.
• What formula describes Snell's Law?

  $n_{1} \sin \theta_{1} =$$n_{2} \sin \theta_{2}$
• What happens to a wave's direction when it moves from a higher to a lower refractive index?

  Bends away from normal
• There is a direct relationship between the refractive index and the speed of light.

  False
• What is the value of the speed of light in a vacuum?

  $2.998 \times 10^{8}$ m/s