The Index of Refraction

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Questions and Answers

What is the primary reason the speed of light changes as it moves from one medium to another?

The frequency of light increases in denser mediums.
The interaction of light with the atoms of the medium. (correct)
The energy of photons increases as they enter a new medium.
The wavelength of light remains constant, but its frequency changes.

The index of refraction for a medium is defined as the ratio of the speed of light in that medium to the speed of light in a vacuum.

False (B)

Explain why the index of refraction is a dimensionless quantity.

The index of refraction is a ratio of two speeds (speed of light in a vacuum and speed of light in a medium), both measured in the same units (m/s). Therefore, the units cancel out, resulting in a dimensionless quantity.

The change in the speed of light at the boundary of a substance causes ______.

refraction Signup and view all the answers

Match the following media with their approximate index of refraction:

Diamond = 2.42 Glass = 1.52 Air/Vacuum = 1.00 Pure Water = 1.33 Signup and view all the answers

Given that the angle of incidence of a light ray from a vacuum into a transparent medium is 45°, and the angle of refraction is 30°, what formula would you use and what additional information do you need to calculate the index of refraction?

Use $n = \frac{\sin i}{\sin R}$; no additional information is needed. (D) Signup and view all the answers

If a material has a higher index of refraction, light will always travel faster through it than through a material with a lower index of refraction.

False (B) Signup and view all the answers

Explain how the index of refraction is related to the optical density of a medium.

The index of refraction is directly related to the optical density of a medium. A higher index of refraction indicates a greater optical density, meaning light travels slower through the medium and bends more when entering it from a less dense medium. Signup and view all the answers

If the speed of light in a particular medium is exactly half the speed of light in a vacuum, the index of refraction of that medium is ______.

2 Signup and view all the answers

Match the following scenarios with the appropriate effect on the angle of refraction assuming light is passing from air into the substance:

Light enters a substance with higher index of refraction = Angle of refraction decreases Light enters a substance with lower index of refraction = Angle of refraction increases Light enters a substance with the same index of refraction as air = No change in the angle of refraction (it remains equal to the angle of incidence) Signup and view all the answers

Which of the following statements correctly describes the relationship between the speed of light, the index of refraction, and the wavelength of light in a medium?

As the index of refraction increases, both the speed and wavelength of light decrease. (C) Signup and view all the answers

The index of refraction of a medium can be less than 1.

False (B) Signup and view all the answers

Describe a situation where knowing the index of refraction of a material is critical for designing optical instruments (such as lenses).

When designing lenses, knowing the index of refraction is crucial for determining how much the light will bend as it passes through the lens. This is essential to ensure that the lens focuses the light correctly to form a clear image. Signup and view all the answers

According to the formula $n = \frac{\sin i}{\sin R}$, if the angle of incidence i is equal to the angle of refraction R, then the index of refraction n is equal to ______.

1 Signup and view all the answers

Match the medium with the effect an increase in its index of refraction has on the speed of light within it:

Increase in refractive index = Results in a decrease in speed of light Signup and view all the answers

If the index of refraction for a certain type of glass is 1.5, and the speed of light in a vacuum is $3.0 \times 10^8$ m/s, what is the speed of light in this glass?

$2.0 \times 10^8$ m/s (A) Signup and view all the answers

The unit for the index of refraction is meters per second (m/s).

False (B) Signup and view all the answers

Explain why different colors of light refract differently when passing through a prism.

Different colors of light have different wavelengths. The index of refraction of a material varies slightly with wavelength, causing different colors to bend at slightly different angles, resulting in dispersion. Signup and view all the answers

The speed of light in sodium chloride is $1.96 \times 10^8$ m/s. Therefore, the index of refraction for sodium chloride is approximately ______.

1.53 Signup and view all the answers

Match each medium with its approximate index of refraction:

Ethyl Alcohol = 1.36 Vegetable Oil = 1.47 Zircon = 1.92 Signup and view all the answers

What would be the speed of light in a medium that has an index of refraction of 2.0?

$1.5 \times 10^8$ m/s (D) Signup and view all the answers

If the index of refraction of substance A is greater than that of substance B, then the wavelength of light will be shorter in substance A than in substance B.

True (A) Signup and view all the answers

Explain how the index of refraction affects the appearance of objects submerged in water.

The index of refraction affects the apparent depth and size of objects submerged in water. Due to refraction, objects appear closer to the surface and may seem larger than they actually are. Signup and view all the answers

According to the formula $n = \frac{c}{v}$, 'c' represents the ______ and 'v' represents the speed of light in a given medium

speed of light in a vacuum Signup and view all the answers

Match the scenarios involving light entering different media with the change (increase/decrease) in its speed:

Light entering from air to diamond. = Speed decreases Light entering from diamond to air. = Speed increases Signup and view all the answers

A light ray travels from air into a glass block with an index of refraction of 1.50. If the angle of incidence is 30°, what is the angle of refraction inside the glass?

19.5° (A) Signup and view all the answers

If the index of refraction of a medium is 1, light does not refract when entering or leaving that medium.

True (A) Signup and view all the answers

How did Foucault's measurement of the speed of light in mediums contribute to the understanding of optics?

Foucault's measurements provided direct evidence that light travels slower in denser media than in a vacuum or air, confirming the wave theory of light and providing a basis for understanding refraction and other optical phenomena. Signup and view all the answers

The index of refraction is also equal to the ratio of the sine of the angle of ______ in a vacuum to the sine of the refracted ray in a medium.

incidence Signup and view all the answers

Associate the following index of refraction with what happens to how light is bent in the medium:

Higher Index = Increases light bending. Lower Index = Decreases light bending. Signup and view all the answers

Flashcards

Index of Refraction

The ratio of the speed of light in a vacuum to the speed of light in a medium.

Dimensionless Quantity

A quantity without any physical dimensions, just a number.