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6.4 Refraction, Reflection, and Absorption

8 min readmarch 30, 2023

Daniella Garcia-Loos

Daniella Garcia-Loos

S

Saarah Hasan

Daniella Garcia-Loos

Daniella Garcia-Loos

S

Saarah Hasan

Refraction, Reflection, and Absorption

When light travels from one medium to another, some of it is transmitted, some is reflected, and some is absorbed.

Reflection—The light bounces off the surface; the reflection of light on a mirrored surface results in the formation of an image.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-bN8NDudobr9S.png?alt=media&token=e122e4de-8d9a-4b01-bb8d-e3f16c5255e8

Taken from pxhere.com

Absorption—The light is converted to another form of energy, usually heat (the light disappears as it enters another medium).

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-n6rrnKpM69sI.png?alt=media&token=1a2341c7-c72e-47a9-8e3d-ff45ecdfa62c

Taken from flickr

Transmission—The light goes right through one medium to another.

Okay, so that was a super brief explanation. Let’s get a bit more in-depth. 🧐

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-jBwCdczP3yUf.png?alt=media&token=bca3cfdd-2cb1-4ff8-9bad-03b8867466e3

Taken from Wikipedia


Reflection and Refraction

Like we mentioned before, light has the ability to seemingly bounce (or reflect) off of a surface. There are two kinds of reflections: specular and diffuse.

Specular—reflections off of a smooth surface; the orientation of the incoming light rays are preserved

Diffuse—reflections off of a rough/uneven surface; the incoming light rays are scattered in different directions.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-vangd3NNT9xU.png?alt=media&token=6e785a7a-d4aa-4c2d-b5af-1be743693f60

Taken from Wikimedia Commons

When light hits a smooth, reflecting surface (), it reflects at the same angle on the other side of the line perpendicular to the surface.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-ScwhwBRMrF2r.png?alt=media&token=8132b596-2cfa-48f6-a526-f82755154e3d

Taken from Wikimedia Commons

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-y8nCv1Bgr38h.png?alt=media&token=7142d2d8-7b5c-4982-9cec-140aaf8cc424

Taken from Wikipedia

In the image above, the light ray approaching the boundary of another medium is the incident ray, and the light ray leaving it is the . At the point where the light ray hits the boundary (the point of incidence), a line perpendicular to the surface can be drawn. This line is known as the , and it divides the angle between the incident ray and into two equal angles. The ray that passes through into the new medium is known as the refracted (or transmitted) ray.

The angle between the incident ray and the is the , the angle between the and the is the , and lastly, the angle between the and the is the .

The states that the (θi​) is equal to the (θr​).

θi=θr

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-ZrevUKjAfLmo.png?alt=media&token=643f7b3e-1337-4d5b-a17e-944171ee40f8

Taken from Wikipedia

Let's expand on the refraction of light. (Here's an interactive.)

Just as we mentioned in 6.1, depends on the medium. When light rays change speed as they travel from one medium to another, the light appears to bend. Refraction is essentially this "bending". However, if there's no change in speed or if the is zero as the light passes from medium to medium, there'll be no refraction.

When light travels from one medium to another and slows down (the is less than the ), the light is been refracted towards the normal. When light travels from one medium to another and speeds up (the is larger than the ), the light is been refracted away from the normal.

When light travels through a material medium, it gets absorbed and re-emitted, which causes its apparent speed v, to be some fraction of c=3.00 * 10⁸ the speed of light traveling through empty space/vacuum). The reciprocal of this fraction, which essentially describe how fast light travels through the material, is the medium’s index of refraction:

n=c/v

Some things to remember about the index of refraction:

  • n has no units.
  • It’s never less than 1, since light always travels slower in a medium than in a vacuum.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-Fd7sQkLfUfc0.png?alt=media&token=508ff57b-6967-4be8-b5fd-569273181c1b

Taken from Wikipedia

The equation that relates the and involves the index of refraction of the incident medium (n₁) and the index of refraction of the refracting medium (n₂​) and is called Snell’s Law:

n₁sinθ₁=n₂sinθ₂

  • If n₂>n₁, θ₂<θ₁ - the ray will refract toward the normal
  • If n₂<n₁, θ₂>θ₁ - the ray will refract away from the normal

Here are some key points about :

  • is a fundamental principle in optics and is used to understand and analyze the behavior of light in different media and to predict the behavior of optical devices and systems. It is a useful tool for designing and troubleshooting optical systems and devices.
  • is based on the principle that the ratio of the sines of the angles of incidence and refraction is equal to the ratio of the refractive indices of the media. This relationship is described by the equation n₁sinθ₁ = n₂sinθ₂, where n₁ and n₂ are the refractive indices of the media, and θ₁ and θ₂ are the angles of incidence and refraction, respectively.
  • is a consequence of the wave nature of light and the fact that light can be reflected and refracted at boundaries between media. It is based on the observation that light is refracted at a certain angle when it is incident on a boundary between two media with different refractive indices.
  • is used to predict the of light when it is incident on a boundary between two media with different refractive indices. It is also used to understand and analyze the behavior of light in different media and to predict the behavior of optical devices and systems.

Total Internal Reflection

As we mentioned previously, when light is refracted from a medium with a high index of refraction to one that has a lower index of refraction, it refracts away from the normal. As the increases, the becomes larger. When the reaches a critical angle, θc​, at which the equals 90 degrees, the refracted beam is directed along the surface.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-2jEBRJOBeflM.png?alt=media&token=bab7447a-bd4f-40ef-9fdf-79ea40388d9c

Taken from Wikimedia Commons

If the exceeds θc​, there is no . The light will be reflected back into the original medium, a phenomenon called .

The critical angle can be found in the equation:

sinθc=n₂/n₁ (n₂<n₁)

If θ₁>θc​, then will occur.

is a phenomenon that occurs when light is incident on a boundary between two media with different refractive indices and is reflected back into the same medium. The critical angle is the at which occurs.

Here are some key points about and critical angles:

  • is a phenomenon that occurs when light is incident on a boundary between two media with different refractive indices and is reflected back into the same medium. It occurs when the is greater than the critical angle.
  • The critical angle is the at which occurs. It is the angle at which the is equal to 90 degrees. The critical angle is determined by the refractive indices of the two media and is given by the equation θc = arcsin(n₂/n₁), where θc is the critical angle, n₁ is the refractive index of the first medium, and n₂ is the refractive index of the second medium.
  • is an important phenomenon in optics and is used in a variety of applications, such as fiber optics, microscopes, and laser systems. It is also used to understand and analyze the behavior of light in different media and to predict the behavior of optical devices and systems.
  • is a consequence of the wave nature of light and the fact that light can be reflected and refracted at boundaries between media. It is based on the observation that light is reflected back into the same medium when it is incident on a boundary at a certain angle.

Practice Problems

1. The critical angle of a material is the for which the is:

A) 0°

B) 30°

C) 45°

D) 90°

E) 180°

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-KjQCeTdrGIrD.png?alt=media&token=eea1c562-c047-41c9-93ba-9ecb16f3a55c


2. A beam of light passes from medium 1 to medium 2 to medium as shown in the accompanying figure. What is true about the respective indices of refraction (n₁, n₂, n₃)?

A) n₁ > n₂ > n₃

B) n₁ > n₃ > n₂

C) n₂ > n₃ > n₁

D) n₂ > n₁ > n₃

E) n₃ > n₁ > n₂


https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-hBGDu4X1wrNy.png?alt=media&token=8e5d249b-9b6f-4792-9f9a-f750dfacc3f9

3. A laser is embedded in a material of index of refraction n. The laser beam emerges from the material and hits a target. See the accompanying figure for the position parameters of the laser and target. The value of n is:

A) 1.4

B) 1.5

C) 2.1

D) 3.5

E) 5.0


4. A wave moves from one medium to a second medium with a different index of refraction. Which of the following wave properties would NEVER change?

A)

B) wavelength

C) speed

D) angle

E) all will change


https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-MQWqZKL1mnv4.png?alt=media&token=271d277d-b9f7-4fe2-812c-c59ffc520241

5. A beam of light passes from medium 1 to medium 2 to medium 3 as shown in the diagram. What may be concluded about the speed of light in each medium?

A) v₃ > v₁ > v₂

B) v₁ > v₂> v₃

C) v₁ > v₃ < v₂

D) v₂ > v₃ > v₁

E) v₂ > v₁ > v₃


6. occurs whenever light is incident on

A) a smooth surface B) a rough surface C) a boundary between high index of refraction and low index of refraction materials D) a boundary between low index of refraction and high index of refraction materials E) a boundary between any two transparent substances, regardless of index of refraction


Answers

  1. D: Definition of critical angle.

  2. D: More–Less dense bend away, Less–More dense bend towards. The more the bend, the bigger the difference in n’s.

  3. B: If you look carefully you can see these are both 3–4–5 triangles and are also the same triangle flipped. The hypotenuse of each is 1.5 m. Using the sides of the triangles, we have sin θ₁ = o/h = 0.8/1.5 for the bottom triangle, and sin θ₂ = o/h = 1.2/1.5 for the top triangle. Now use n₁ sin θ₁ = n₂ sin θ₂ … n₁ (0.8/1.5) = (1) (1.2/1.5) … n₁ = 1.2/0.8=3/2=1.5

  4. A: Fact for refraction problems

  5. A: More–Less dense bend away, Less–More dense bend towards. The more the bend, the bigger the difference in n’s … this shows that n₂ > n₁ > n₃. More n means less speed so v₃ > v₁ > v₂

  6. A: Fact about


Key Terms to Review (14)

Angle of incidence

: The angle of incidence is the angle between an incoming ray of light or other electromagnetic wave and a line perpendicular to the surface it strikes. It describes how the wave approaches the boundary or interface between two different mediums.

Angle of reflection

: The angle of reflection refers to the angle formed between an outgoing ray or reflected wave and a line perpendicular to a reflecting surface. It represents how light bounces off or reflects from a surface.

Angle of refraction

: The angle of refraction refers to the angle between a refracted ray and a line perpendicular to the surface it enters. It occurs when light passes from one medium into another, causing its direction to change.

Critical angle (θc)

: The critical angle is defined as the minimum angle of incidence at which total internal reflection occurs. It is determined by comparing the indices of refraction between two media.

Frequency

: Frequency refers to the number of cycles or oscillations of a wave that occur in one second. It is measured in hertz (Hz).

Index of refraction (n)

: The index of refraction (n) is defined as the ratio of the speed of light in vacuum to its speed in another medium. It quantifies how much light slows down when passing through different materials.

Law of reflection

: The law of reflection states that the angle of incidence (the incoming angle) is equal to the angle of reflection (the outgoing angle) when light reflects off a surface.

Normal line

: The normal line is an imaginary line perpendicular (at 90 degrees) to a surface at any given point. It serves as reference for measuring angles during reflection and refraction.

Reflected ray

: The reflected ray is the ray of light that bounces off a surface after striking it. It follows the law of reflection, which states that the angle of incidence is equal to the angle of reflection.

Refracted ray

: The refracted ray is the bent path taken by light as it passes from one medium to another with different optical densities. It occurs due to a change in speed and direction.

Snell's Law

: Snell's Law relates the angles at which light rays enter and exit different mediums, describing how they refract (bend) due to changes in speed.

Specular Reflection

: Specular reflection refers to the reflection of light off a smooth surface, where the angle of incidence is equal to the angle of reflection.

Total internal reflection

: Total internal reflection occurs when a light ray traveling in a medium strikes an interface with another medium at an angle greater than or equal to the critical angle. Instead of refracting, the light is reflected back into the original medium.

Wave speed

: Wave speed refers to how fast a wave travels through a medium. It is determined by dividing the distance traveled by the time taken for one complete cycle of oscillation.

6.4 Refraction, Reflection, and Absorption

8 min readmarch 30, 2023

Daniella Garcia-Loos

Daniella Garcia-Loos

S

Saarah Hasan

Daniella Garcia-Loos

Daniella Garcia-Loos

S

Saarah Hasan

Refraction, Reflection, and Absorption

When light travels from one medium to another, some of it is transmitted, some is reflected, and some is absorbed.

Reflection—The light bounces off the surface; the reflection of light on a mirrored surface results in the formation of an image.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-bN8NDudobr9S.png?alt=media&token=e122e4de-8d9a-4b01-bb8d-e3f16c5255e8

Taken from pxhere.com

Absorption—The light is converted to another form of energy, usually heat (the light disappears as it enters another medium).

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-n6rrnKpM69sI.png?alt=media&token=1a2341c7-c72e-47a9-8e3d-ff45ecdfa62c

Taken from flickr

Transmission—The light goes right through one medium to another.

Okay, so that was a super brief explanation. Let’s get a bit more in-depth. 🧐

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-jBwCdczP3yUf.png?alt=media&token=bca3cfdd-2cb1-4ff8-9bad-03b8867466e3

Taken from Wikipedia


Reflection and Refraction

Like we mentioned before, light has the ability to seemingly bounce (or reflect) off of a surface. There are two kinds of reflections: specular and diffuse.

Specular—reflections off of a smooth surface; the orientation of the incoming light rays are preserved

Diffuse—reflections off of a rough/uneven surface; the incoming light rays are scattered in different directions.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-vangd3NNT9xU.png?alt=media&token=6e785a7a-d4aa-4c2d-b5af-1be743693f60

Taken from Wikimedia Commons

When light hits a smooth, reflecting surface (), it reflects at the same angle on the other side of the line perpendicular to the surface.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-ScwhwBRMrF2r.png?alt=media&token=8132b596-2cfa-48f6-a526-f82755154e3d

Taken from Wikimedia Commons

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-y8nCv1Bgr38h.png?alt=media&token=7142d2d8-7b5c-4982-9cec-140aaf8cc424

Taken from Wikipedia

In the image above, the light ray approaching the boundary of another medium is the incident ray, and the light ray leaving it is the . At the point where the light ray hits the boundary (the point of incidence), a line perpendicular to the surface can be drawn. This line is known as the , and it divides the angle between the incident ray and into two equal angles. The ray that passes through into the new medium is known as the refracted (or transmitted) ray.

The angle between the incident ray and the is the , the angle between the and the is the , and lastly, the angle between the and the is the .

The states that the (θi​) is equal to the (θr​).

θi=θr

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-ZrevUKjAfLmo.png?alt=media&token=643f7b3e-1337-4d5b-a17e-944171ee40f8

Taken from Wikipedia

Let's expand on the refraction of light. (Here's an interactive.)

Just as we mentioned in 6.1, depends on the medium. When light rays change speed as they travel from one medium to another, the light appears to bend. Refraction is essentially this "bending". However, if there's no change in speed or if the is zero as the light passes from medium to medium, there'll be no refraction.

When light travels from one medium to another and slows down (the is less than the ), the light is been refracted towards the normal. When light travels from one medium to another and speeds up (the is larger than the ), the light is been refracted away from the normal.

When light travels through a material medium, it gets absorbed and re-emitted, which causes its apparent speed v, to be some fraction of c=3.00 * 10⁸ the speed of light traveling through empty space/vacuum). The reciprocal of this fraction, which essentially describe how fast light travels through the material, is the medium’s index of refraction:

n=c/v

Some things to remember about the index of refraction:

  • n has no units.
  • It’s never less than 1, since light always travels slower in a medium than in a vacuum.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-Fd7sQkLfUfc0.png?alt=media&token=508ff57b-6967-4be8-b5fd-569273181c1b

Taken from Wikipedia

The equation that relates the and involves the index of refraction of the incident medium (n₁) and the index of refraction of the refracting medium (n₂​) and is called Snell’s Law:

n₁sinθ₁=n₂sinθ₂

  • If n₂>n₁, θ₂<θ₁ - the ray will refract toward the normal
  • If n₂<n₁, θ₂>θ₁ - the ray will refract away from the normal

Here are some key points about :

  • is a fundamental principle in optics and is used to understand and analyze the behavior of light in different media and to predict the behavior of optical devices and systems. It is a useful tool for designing and troubleshooting optical systems and devices.
  • is based on the principle that the ratio of the sines of the angles of incidence and refraction is equal to the ratio of the refractive indices of the media. This relationship is described by the equation n₁sinθ₁ = n₂sinθ₂, where n₁ and n₂ are the refractive indices of the media, and θ₁ and θ₂ are the angles of incidence and refraction, respectively.
  • is a consequence of the wave nature of light and the fact that light can be reflected and refracted at boundaries between media. It is based on the observation that light is refracted at a certain angle when it is incident on a boundary between two media with different refractive indices.
  • is used to predict the of light when it is incident on a boundary between two media with different refractive indices. It is also used to understand and analyze the behavior of light in different media and to predict the behavior of optical devices and systems.

Total Internal Reflection

As we mentioned previously, when light is refracted from a medium with a high index of refraction to one that has a lower index of refraction, it refracts away from the normal. As the increases, the becomes larger. When the reaches a critical angle, θc​, at which the equals 90 degrees, the refracted beam is directed along the surface.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-2jEBRJOBeflM.png?alt=media&token=bab7447a-bd4f-40ef-9fdf-79ea40388d9c

Taken from Wikimedia Commons

If the exceeds θc​, there is no . The light will be reflected back into the original medium, a phenomenon called .

The critical angle can be found in the equation:

sinθc=n₂/n₁ (n₂<n₁)

If θ₁>θc​, then will occur.

is a phenomenon that occurs when light is incident on a boundary between two media with different refractive indices and is reflected back into the same medium. The critical angle is the at which occurs.

Here are some key points about and critical angles:

  • is a phenomenon that occurs when light is incident on a boundary between two media with different refractive indices and is reflected back into the same medium. It occurs when the is greater than the critical angle.
  • The critical angle is the at which occurs. It is the angle at which the is equal to 90 degrees. The critical angle is determined by the refractive indices of the two media and is given by the equation θc = arcsin(n₂/n₁), where θc is the critical angle, n₁ is the refractive index of the first medium, and n₂ is the refractive index of the second medium.
  • is an important phenomenon in optics and is used in a variety of applications, such as fiber optics, microscopes, and laser systems. It is also used to understand and analyze the behavior of light in different media and to predict the behavior of optical devices and systems.
  • is a consequence of the wave nature of light and the fact that light can be reflected and refracted at boundaries between media. It is based on the observation that light is reflected back into the same medium when it is incident on a boundary at a certain angle.

Practice Problems

1. The critical angle of a material is the for which the is:

A) 0°

B) 30°

C) 45°

D) 90°

E) 180°

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-KjQCeTdrGIrD.png?alt=media&token=eea1c562-c047-41c9-93ba-9ecb16f3a55c


2. A beam of light passes from medium 1 to medium 2 to medium as shown in the accompanying figure. What is true about the respective indices of refraction (n₁, n₂, n₃)?

A) n₁ > n₂ > n₃

B) n₁ > n₃ > n₂

C) n₂ > n₃ > n₁

D) n₂ > n₁ > n₃

E) n₃ > n₁ > n₂


https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-hBGDu4X1wrNy.png?alt=media&token=8e5d249b-9b6f-4792-9f9a-f750dfacc3f9

3. A laser is embedded in a material of index of refraction n. The laser beam emerges from the material and hits a target. See the accompanying figure for the position parameters of the laser and target. The value of n is:

A) 1.4

B) 1.5

C) 2.1

D) 3.5

E) 5.0


4. A wave moves from one medium to a second medium with a different index of refraction. Which of the following wave properties would NEVER change?

A)

B) wavelength

C) speed

D) angle

E) all will change


https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-MQWqZKL1mnv4.png?alt=media&token=271d277d-b9f7-4fe2-812c-c59ffc520241

5. A beam of light passes from medium 1 to medium 2 to medium 3 as shown in the diagram. What may be concluded about the speed of light in each medium?

A) v₃ > v₁ > v₂

B) v₁ > v₂> v₃

C) v₁ > v₃ < v₂

D) v₂ > v₃ > v₁

E) v₂ > v₁ > v₃


6. occurs whenever light is incident on

A) a smooth surface B) a rough surface C) a boundary between high index of refraction and low index of refraction materials D) a boundary between low index of refraction and high index of refraction materials E) a boundary between any two transparent substances, regardless of index of refraction


Answers

  1. D: Definition of critical angle.

  2. D: More–Less dense bend away, Less–More dense bend towards. The more the bend, the bigger the difference in n’s.

  3. B: If you look carefully you can see these are both 3–4–5 triangles and are also the same triangle flipped. The hypotenuse of each is 1.5 m. Using the sides of the triangles, we have sin θ₁ = o/h = 0.8/1.5 for the bottom triangle, and sin θ₂ = o/h = 1.2/1.5 for the top triangle. Now use n₁ sin θ₁ = n₂ sin θ₂ … n₁ (0.8/1.5) = (1) (1.2/1.5) … n₁ = 1.2/0.8=3/2=1.5

  4. A: Fact for refraction problems

  5. A: More–Less dense bend away, Less–More dense bend towards. The more the bend, the bigger the difference in n’s … this shows that n₂ > n₁ > n₃. More n means less speed so v₃ > v₁ > v₂

  6. A: Fact about


Key Terms to Review (14)

Angle of incidence

: The angle of incidence is the angle between an incoming ray of light or other electromagnetic wave and a line perpendicular to the surface it strikes. It describes how the wave approaches the boundary or interface between two different mediums.

Angle of reflection

: The angle of reflection refers to the angle formed between an outgoing ray or reflected wave and a line perpendicular to a reflecting surface. It represents how light bounces off or reflects from a surface.

Angle of refraction

: The angle of refraction refers to the angle between a refracted ray and a line perpendicular to the surface it enters. It occurs when light passes from one medium into another, causing its direction to change.

Critical angle (θc)

: The critical angle is defined as the minimum angle of incidence at which total internal reflection occurs. It is determined by comparing the indices of refraction between two media.

Frequency

: Frequency refers to the number of cycles or oscillations of a wave that occur in one second. It is measured in hertz (Hz).

Index of refraction (n)

: The index of refraction (n) is defined as the ratio of the speed of light in vacuum to its speed in another medium. It quantifies how much light slows down when passing through different materials.

Law of reflection

: The law of reflection states that the angle of incidence (the incoming angle) is equal to the angle of reflection (the outgoing angle) when light reflects off a surface.

Normal line

: The normal line is an imaginary line perpendicular (at 90 degrees) to a surface at any given point. It serves as reference for measuring angles during reflection and refraction.

Reflected ray

: The reflected ray is the ray of light that bounces off a surface after striking it. It follows the law of reflection, which states that the angle of incidence is equal to the angle of reflection.

Refracted ray

: The refracted ray is the bent path taken by light as it passes from one medium to another with different optical densities. It occurs due to a change in speed and direction.

Snell's Law

: Snell's Law relates the angles at which light rays enter and exit different mediums, describing how they refract (bend) due to changes in speed.

Specular Reflection

: Specular reflection refers to the reflection of light off a smooth surface, where the angle of incidence is equal to the angle of reflection.

Total internal reflection

: Total internal reflection occurs when a light ray traveling in a medium strikes an interface with another medium at an angle greater than or equal to the critical angle. Instead of refracting, the light is reflected back into the original medium.

Wave speed

: Wave speed refers to how fast a wave travels through a medium. It is determined by dividing the distance traveled by the time taken for one complete cycle of oscillation.


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AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.