Students easily control observations involving simple refraction and total internal reflection. Scattering agent added to water in the plastic tank make laser beams visible. At the critical angle, the refracted ray appears along the boundary and further increases in the angle of incidence shows that the refracted ray disappears.ĭesigned by California Physics Teacher Dean Baird, this versatile system allows students to see and control light beams. As the angle continues to increase, the refracted light becomes dimmer and dimmer and the reflected light becomes brighter and brighter. As angles get larger, the reflected light at the glass-to-air boundary becomes visible. The angle of incidence at the glass-to-air boundary begins at 0° and is slowly increased. The demonstration is performed on top of paper with angle markings. Refraction occurs at the flat edge of the block. The light approaches along the curved side of the cylinder along the radial line so that there is no refraction upon entering the block. This 1.5-minute video features a demonstration in which a beam of light is directed into a hemicylindrical block of glass. The 3-minute video is from the Physics Demos YouTube channel. Edwards does several light-piping demonstrations and explains the physics behind each. Edwards explains the importance of total internal reflection and its application to optical fibers. Total Internal Reflection Demo: Optical Fibers.Numerous engineering and communication applications are discussed. Reflection and refraction and total internal reflection are masterfully explained. The highlight of the 5-minute YouTube video is the demonstration of light piping through a liquid stream of propylene glycol. A sample problem is performed to determine the critical angle for the water-air boundary.īill Hammack from the Department of Chemical and Biomolecular Engineering at the University of Illinois explains how optical fibers work and how engineers use them to send messages. The critical angle is defined and then derived from Snell's Law. This 10-minute video by Step-by-Step Science discusses the reflection and refraction of light at a boundary and uses several diagrams to demonstrate how an increase in the angle of incidence increases both the brightness of the reflected ray and the angle of refraction. Other options are available that do not necessarily shine light upon the topic of total internal reflection. Light meters allow users to quantitatively measure the intensity of the reflected and refracted light relative to the incident light intensity. Angles of incidence, reflection, and refraction can be measured with a built-in protractor. Users can choose from some pre-selected materials or choose a customized index of refraction value. This Interactive tool allows the user to explore the reflection and refraction of light at a boundary. The Interactive comes with a ready-to-use activity that directs the learner towards the key observations to be found in the Interactive. The brightness of the three rays are indicated on the display.Learners can quickly observe that increasing the angle of incidence leads to an increase in the angle of refraction but also to a dimmer refracted ray and a brighter reflected ray. A protractor allows for the easy measurement of the angles of incidence, reflection and refraction. A laser can be dragged to any angle and a ray directed towards the boundary. Several substances can be chosen as the "Top" and "Bottom" substance. This simulation from The Physics Classroom allows a learner to explore the reflection and refraction of light at a boundary. Refraction Interactive, The Physics Classroom.The Physics Classroom Tutorial, Refraction and the Ray Model of Light Chapter, Lesson 3.
Readings from The Physics Classroom Tutorial
To describe how the relative intensity of a reflected ray and refracted ray at a boundary is dependent upon the angle of incidence.Total Internal Reflection - Complete Toolkit Teacher Toolkits » Total Internal Reflection
0 kommentar(er)
