When light propagates through two adjacent materials that have different optical properties, some interesting phenomena occur at the interface separating the two materials. For example, consider a ray of light that travels from air into the water of a lake. As the ray strikes the air-water interface (the surface of the lake), it is partly reflected back into the air and partly refracted or transmitted into the water. This explains why on the surface of a lake sometimes you see the reflection of the surrounding landscape and other times the underwater vegetation. These effects on light propagation occur because light travels at different speeds depending on the medium. The index of refraction of a material, denoted by n. gives an indication of the speed of light in the material. It is defined as the ratio of the speed of light e in vacuum to the speed in the material, or Figure incident ray interface normal n= 0₁ 등.. ea reflected ray refracted ray < 1 of 1 > Is light always both reflected and refracted at the interface separating two different materials? To answer this question, let's consider the case of light propagating from a certain index of refraction (ie., ₁ > 1₂). Part F Correct The greater the change in index of refraction, the greater the change in the direction of propagation of light. To avoid or minimize undesired bending of the light rays. matching indices of refraction. In the case of >2, if the incidence angle is increased, the angle of refraction ▸ View Available Hint(s) O decreases. Ⓒincreases. increases up to a maximum value of 90 degrees. Ⓒremains constant. Submit ✓ Correct Since the light is propagating into a material with a smaller index of refraction, the angle of refraction, 8₂, is always greater than the angle of incidence, ₁. Therefore will reach its maximum value of 90° and the refracted ray will travel along the interface. The angle of incidence for which 08₂ = 90° is called the critical angle cr. F Berik, no refraction occurs. The ray no longer passes into the second material. Instead, it is completely reflected back into the original material. This phenomenon is only when light encounters an interface with a second material with a smaller index of refraction than the original material. Part G What is the critical angle crit for light propagating from a material with index of refraction of 1.50 to a material with index of refraction of 1.00? Express your answer in radians. ▸ View Available Hint(s) Bcrit = Previous Answers Submit for Part for Part Go for Part&redo fort G reser Part G keyboard shortcuts for Part G help for Part G Provide Feedback radians