Physics
Refraction is the bending of light, which occurs when light changes speed as it passes from a material with one index of refraction to a new material with a different index of refraction. The index of refraction (denoted as lowercase 'n') describes how fast light travels through a material and can be found by calculating the ratio of the speed of light in a vacuum to the actual speed of light in that material. This value is always greater than one, as the true speed of light is always less than 'c' (speed of light in a vacuum).
Snell's Law is used to calculate the angle light will bend at when it travels from one material to another. It states that n1sin(θ1) = n2sin(θ2) In certain situations, the math of Snell's Law doesn't work, because refraction is impossible. In these cases, all light is reflected within the substance it initially traveled through, which is called total internal reflection.
Lesson Outline
<ul> <li>Introduction to refraction and Snell's Law</li> <li>Speed of light and its relationship with refraction <ul> <li>Constant c: speed of light in a vacuum</li> <li>Speed of light is not a constant on Earth</li> <li>Light moves slower through different materials</li> </ul> </li> <li>Index of refraction <ul> <li>Denoted with lowercase 'n'</li> <li>Describes how fast light travels through a material</li> <li>Calculated as the ratio of the speed of light in a vacuum to the actual speed of light in that material (n = c/v)</li> <li>Value is always greater than one</li> </ul> </li> <li>Refraction explained <ul> <li>Bending of light</li> <li>Occurs when light changes speed and travels through materials with different indices of refraction</li> </ul> </li> <li>Snell's Law <ul> <li>Used to calculate the angle light will bend at when it travels from one material to another</li> <li>Formula: n<sub>1</sub>sin(θ<sub>1</sub>) = n<sub>2</sub>sin(θ<sub>2</sub>)</li> <li>Measure theta from the normal line</li> </ul> </li> <li>Breaking Snell's Law and total internal reflection <ul> <li>Impossible refraction leads to total internal reflection</li> <li>Light reflects off the boundary and stays in material one</li> </ul> </li> </ul>
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FAQs
Refraction is the bending of light as it passes from one substance to another due to a change in the speed of light. When light enters a substance with a different index of refraction, its speed changes, causing it to change direction. The greater the difference in the indices of refraction between the two substances, the more noticeable the bending of light will be.
Snell's Law describes the relationship between the angles of incidence and refraction when light passes through the interface between two substances with different indices of refraction. It is represented mathematically as n1 * sin(θ1) = n2 * sin(θ2), where n1 and n2 are the indices of refraction of the two substances, and θ1 and θ2 are the angles of incidence and refraction, respectively. By knowing the indices of refraction and one of the angles, the other angle can be calculated using Snell's Law.
Total internal reflection is a phenomenon that occurs when light traveling from a substance with a higher index of refraction to a substance with a lower index of refraction reaches a critical angle at the interface. At this angle, the refracted light travels along the interface, and any increase in the angle of incidence results in the light being completely reflected back into the higher index of refraction substance. Total internal reflection is important in various applications, such as fiber-optics and prisms, where efficient light transmission and manipulation are required.
