One of the most common applications of total internal reflection is in fibre optics. Alevel physics revision edexcel physics alevel revision notes. Snell s law, in optics, a relationship between the path taken by a ray of light in crossing the boundary or surface of separation between two contacting substances and the refractive index of each. Using snells law to predict an angle value as with any equation in physics, the snells law equation is valued for its predictive ability. A whole lesson, lesson plan included, on refraction and snells law. An objects index of refraction is described using snells law, which relates the speed of light in a material to the speed of light in a vacuum. Geometrical light rays fermats principle of least time fermats principle applied to reflection and refraction snells law examples imaging and the lens law the lens makers formula thin lens and keys for ray tracing optical. History of snell s law snell s law describing refraction was first recorded by ptolemy in 140 a. Light rays represent the direction of travel of the waterfronts. For manual work, the doflimits are usually indicated on the. The pdf version of the teacher toolkit on the topic of refraction and snells law is displayed below. Application of these principles through the use of a polarizing microscope allows geologists to confirm the hand specimen identification of minerals, to.
Physics notes physics notes form 3 physics notes form 3 klb physics notes form 3 pdf physics notes form 4 physics notes form 4 chapter 2 physics notes form 4 klb physics notes form 4 pdf physics notes form 4 pdf physics notes form four physics notes form four klb. Wave theory of light is used to explain the reflection and refraction of light. Electromagnetic waves, snell s law we now embark on a fourweek digression to consider the physics of the interaction of light with nonopaque minerals. From work on relative refractive index, back to top. If light is propagating from a more dense to a less dense medium in the optical sense, i.
As with any equation in physics, the snells law equation is valued for its predictive ability. Snells law has a wide range of applications in physics especially in the. For the best revision experience, use both the notes and the videos at the same time to help you follow along. If you have other applications, or relevant sources, please do bring them up. Snells law, in optics, a relationship between the path taken by a ray of light in crossing the boundary or surface of separation between two contacting substances and the refractive index of each. The change in direction or bending of a light wave passing from one transparent medium to another. Snells law and the index of refraction introduction. The light is bending away from the normal as it enters a rarer material. If we label the angle of incidence as i and the angle of refraction as r, then it can be shown that when travelling from a vacuum into a material, the ratio remains constant for all values of i. Snells law is a relationship between the angles of incidence and refraction and the. All physics formulas pdf formula of mean median and mode. Refraction a2levellevelrevision, physics, particles. I have some notes written for the old spec on my blog here on tsr called kyxs university experience. Ordinary level physics lecturers notes 1st edition s3 by peter abraham in.
Image formation due to refraction application of refraction 3. Snell s law was used to calculate the angle of refraction. To answer this question, well need to make use of snells law. Thus to find the refractive index of our new plastic, we need to divide the speed of light in a vacuum c, by the speed that light travels in the medium v. Notice that this time, the angle of refraction is larger than the angle of incidence. The best physics o level notes compiled from all around the world at one place for your ease so you can prepare for your tests and examinations with the satisfaction that you have the best resources available to you. Snells law applies to the refraction of light in any situation, regardless of what the two media are. Snells law and the refractive index so we know that waves slow down when they enter optically denser materials, and bend towards the normal line. Transverse and longitudinal waves, oscillating systems, phase difference, the wave equation, the electromagnetic spectrum and its uses and dangers, reflection and refraction, refractive index, snells law, measuring refractive index, critical angles, total internal reflection, polarisation, using polarised light, pulseecho techniques, ultrasound. Alevel physics revision notes 2015 scool the revision. The physics classroom grants teachers and other users the right to print this pdf document and to download this pdf document for private use. The frequency f of such strip oscillations can be empirically related to the length l. Furthermore, is the angle of the incident light ray from air with respect to the normal, while is the angle of the refracted ray in.
D first described by relationship by snellius in 1621 first explained in 1650 by fermats principle of least time. It is shown that the sizes of the angles of incidence and refraction are related to the speed of the light through the medium. The refractive index can be calculated from the sin of the angles of the light measured in the materials. One important consequence of snells law of refraction is the phenomenon of total internal re. Snell s law and the refractive index so we know that waves slow down when they enter optically denser materials, and bend towards the normal line. See more ideas about physics, a level physics and chemistry. Refraction revision and snells law introduction lesson. In your igcse examination you might be asked to describe an experiment to investigate snells law or determine the refractive index of a. At a certain angle of incidence called the critical angle, the light. The best physics o level notes o and a level notes. If any three of the four variables in the equation are known, the fourth variable can be predicted if appropriate problemsolving skills are employed. Waves can pass through other waves, like ripples on a pond, with their combined amplitude the sum of the individual dispacements at any one time the principle of superposition. Refraction, geometrical optics from alevel physics tutor. Does anyone know any links websites to notes for the aqa physics alevel course the course that started in september 2016.
But can we predict how far waves will change direction. The study of physics enables learners to be creative and innovative in industry and society can. One of the most important parameters that measures optical properties of a medium is the index of refraction. See more ideas about physics, physics notes and physical science. Pdf ordinary level physics lecturers notes 1 st edition peter. In figure 314a, point object s sends nonparallel rays toward a plane mirror, which reflects them as. This important law, named after dutch mathematician willebrord snell. Sound diffracts so much that snells law is seldom a useful approximation to sound wave behavior.
An optical fibre is a thin, transparent fibre, usually made of glass or plastic, for transmitting light. The ratio constant is called the relative refractive index n. Where and represent the index of refraction for air and water, respectively. Solving more numerical will help the student in understanding snells law. Light rays travel in different mediums at different speeds. Each lesson includes informative graphics, occasional animations and videos, and check your understanding sections that allow the user to practice what is.
Electromagnetic waves in vacuum always propagate with speed c 3. The best physics as and a level notes, revision guides, tips and websites compiled from all around the world at one place for your ease so you can prepare for your tests and examinations with the satisfaction that you have the best resources available to you. Snells law relates the angle of incidence and the angle of refraction to the refractive index of a medium by sin where i is the angle of incidence and r is the angle of refraction. The physics classroom teacher toolkits snells law snells law pdf version. Snells law also known as snelldescartes law and the law of refraction is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media, such as water, glass, or air in optics, the law is used in ray tracing to compute the angles of incidence or. Went through ppt with students to the direction of bending. Total internal reflection in glass depends on the fact that its critical angle. If we label the angle of incidence as i and the angle of refraction as r, then it can be shown that when travelling from a vacuum into a material, the ratio remains constant for all.
Alevel physics advancing physicsrefraction wikibooks, open. Refraction calculations and total internal reflection s. Refraction of light rays, examples and solutions physics. The ratio sin isin r is a constant snells law refractive index n n sin isin r n cv.
Total internal reflection is a very useful natural phenomenon since it can be used to confine light. When the effect of lenses or mirrors on paths, we consider the drawing of diagrams using light rays and normals. From snells law, the angle of refraction can be calculated if the refractive index of the two materials is known. This law also applies to the bending of light by lenses and to the guiding of light by the fiber optic cables that carry modern communications signals. Conceptual ideas develop logically and sequentially, ultimately leading into the mathematics of the topics. An alternative discussion of snells law could be to discuss.
Powerpoint revises refraction and the direction of bending, then introduces snells law. Refractive index snells law group experiment lesson 5 3. We can derive it by considering a spherical wave emanating from the center of the sphere with the same radius r 1. Emission rate photonss in a normal and offnormal direction.
Using snells law, determine the constant when the angle of incidence and the angle of refraction are. One important consequence of snells law of refraction is the phenomenon of. Physics notes form 3 free download kcse revision notes pdf. The incident ray, refracted ray and normal all lie in the same plane. Snells law relates the angle of incidence to the angle of refraction. Lets make a ratio of the two refractive indices the two n values for the air and water.
An example to understand this better is that of placing a strawstick in a glass of water wherein it to be bent when viewed from any other angle than 90 0 to the surface. Snells law a monochromatic light ray passes from air n 1. Snells law this equation shows the inverse relationship between the angles and indices. This section considers electromagnetic waves from radio through to gamma. This law was discovered in 1621 by the dutch astronomer and mathematician willebrord snell also called snellius.433 1555 1184 687 865 1063 1285 216 93 1169 482 1553 1454 393 435 1204 1009 1688 30 1263 1455 888 1336 1310 784 329 1030 187 166 39 651