Question
11.2 Refraction - What is refraction and is it related to the speed of light?Define index of refraction. - Solve problems involving the index of refraction (n=c/v) using GRASP - What is Total Internal Reflection? How is this related to the critical angle?
Solution
4.1
(361 Votes)
Xavier
Expert · Tutor for 3 years
Answer
**11.2 Refraction****What is refraction and is it related to the speed of light?**Refraction is the bending of light as it passes from one transparent medium to another. This bending occurs because the speed of light changes as it enters a different medium. Light travels slower in denser mediums and faster in less dense mediums. The change in speed causes a change in direction, which we perceive as bending. So yes, refraction is directly related to the speed of light in different media.**Define index of refraction.**The index of refraction (represented by the symbol 'n') of a material is a dimensionless number that describes how light propagates through that medium. It's defined as the ratio of the speed of light in a vacuum (c) to the speed of light in the medium (v): n = c/vA higher index of refraction indicates that light travels slower in that medium. For example, the index of refraction of air is approximately 1 (very close to a vacuum), while the index of refraction of water is about 1.33, and for diamond, it's around 2.42.**Solve problems involving the index of refraction (n=c/v) using GRASP.**GRASP stands for:* **Given:** List the known quantities and variables provided in the problem.* **Required:** State what the problem is asking you to find.* **Analysis:** Identify the relevant equations and principles that apply to the problem. In this case, it's the index of refraction equation: n = c/v.* **Solution:** Substitute the given values into the equation and solve for the unknown variable.* **Paraphrase:** Restate the answer in a clear and concise sentence, including units.**Example Problem:**Light travels through a glass block at a speed of 2.0 x 10⁸ m/s. What is the index of refraction of the glass?* **Given:** v = 2.0 x 10⁸ m/s, c = 3.0 x 10⁸ m/s (speed of light in a vacuum)* **Required:** n (index of refraction of the glass)* **Analysis:** n = c/v* **Solution:** n = (3.0 x 10⁸ m/s) / (2.0 x 10⁸ m/s) = 1.5* **Paraphrase:** The index of refraction of the glass is 1.5.**What is Total Internal Reflection? How is this related to the critical angle?**Total internal reflection (TIR) is a phenomenon that occurs when light traveling from a denser medium to a less dense medium strikes the boundary at an angle greater than a specific angle called the critical angle. Instead of refracting (bending away from the normal) into the less dense medium, the light is completely reflected back into the denser medium.The critical angle is the angle of incidence at which the angle of refraction is 90 degrees. In other words, the refracted light ray travels along the boundary between the two media. Any angle of incidence greater than the critical angle will result in total internal reflection.The critical angle (θc) can be calculated using Snell's Law and is related to the indices of refraction of the two media:sin(θc) = n₂/n₁where n₁ is the index of refraction of the denser medium (where the light originates) and n₂ is the index of refraction of the less dense medium. TIR only occurs when n₁ > n₂.Examples of total internal reflection include the sparkle in diamonds and the transmission of light through optical fibers.