The Plane Mirror Images simulation blends an interactive Tutorial with an interactive simulation. Students will learn about the law of reflection and how it can be used to determine the location and characteristics of an image formed by a plane mirror.Ellipse Reflection Model. Move the points. Adjust number of segments. Press Play. This is a computer model of how sound (or light, etc) reflects inside an ellipse. Points "F" and "G" are the focus points of the ellipse. Example: Stand at one focus point in an elliptical room. A friend could stand at the other focus point and whisper: you would ... The light ray reflecting away from the mirror is called the reflected ray. What is the Normal, Angle of Incidence and Reflection? A normal is a line drawn perpendicular to the reflective surface at the point where incident ray hits the surface.Simulate the reflection of light on a mirror. Mirror (Curved) A mirror whose shape is curved. Can be circular, parabolic, or defined by a custom equation y = f (x). Ideal curved mirror The idealized "curved" mirror which obeys exactly the mirror equation (1/p + 1/q = 1/f). The focal length (in pixels) can be set directly. Beam SplitterExplore bending of light between two media with different indices of refraction. See how changing from air to water to glass changes the bending angle. Play with prisms of different shapes and make rainbows. Join photographer Nicholas on his expedition to Antarctica to photograph the wildlife. In this simulation, you will learn about the wave-like behaviors of light. When light travels from one medium into another, the rays can reflect off of the surface. Depending on the angle and the media, the light can also refract.This pathway provides resources for understanding motion in one dimension. The fundamentals of vector and scalars are covered, and the key concepts of position, displacement, speed, velocity and acceleration are explained. The pathway concludes with a series of questions to test understanding of the topic. 6 Favorites.The law of reflection states that the angle of reflection (θ r) equals the angle of incidence (θ i), θ r = θ i (1) The normal, incident ray and reflected ray all lie in the same plane (Fig. 1). In this lab, you will study the image formation by plane mirrors using an online simulation (Fig. 2 below). Fig. 1: Reflection of light from a ...By converting our sims to HTML5, we make them seamlessly available across platforms and devices. Whether you have laptops, iPads, chromebooks, or BYOD, your favorite PhET sims are always right at your fingertips.Become part of our mission today, and transform the learning experiences of students everywhere! cal simulation of light scattering by multiple wavelength-sized particles near or between planar interfaces. It im-plements the superposition T-matrix method [15, 16, 17] Krzysztof Czajkowski and Dominik Theobald contributed equally to this work. Figure 1: Artistic visualization of a Gaussian beam scattered by multiple particles on a substrate.This is a simple simulation showing the reflection and refraction of a ray of light as it attempts to move from one medium to another. Use the sliders to adjust the index of refraction of each of the two materials, as well as the angle of incidence (the angle between the incident ray of light and the normal to the surface).The Plane Mirror Images simulation blends an interactive Tutorial with an interactive simulation. Students will learn about the law of reflection and how it can be used to determine the location and characteristics of an image formed by a plane mirror.Simulation of image formation in concave and convex mirrors. Move the tip of the Object arrow or the point labeled focus. Move the arrow to the right side of the mirror to get a convex mirror. Bending Light 1.1.29 - PhET Interactive SimulationsRegular and Diffused Reflection. The light gets reflected from the surfaces. Any surface which is polished or in other words is shiny always acts like a mirror. The observation of light bouncing off the surfaces is termed reflection. The light after reflection travels in the same medium from where the ray was incident on the surface.Reflection of light (and other forms of electromagnetic radiation) occurs when the waves encounter a surface or other boundary that does not absorb the energy of the radiation and bounces the waves away from the surface. The simplest example of visible light reflection is the surface of a smooth pool of water, where incident light is reflected ...How does a lens or mirror form an image? See how light rays are refracted by a lens or reflected by a mirror. Observe how the image changes when you adjust the focal length of the lens, move the object, or move the screen.Light. Light Mixing; Color Pigment Mixing; Polarization of Light; Double Slit Diffraction and Interference; Double Slit Interference; Diffraction Grating Laser Lab; Thin Film interference; Reflection and Refraction; Dispersion of Light; Plane Mirrors; Concave and Convex Mirrors; iPad Spherical Mirror Simulation; Concave and Convex Lenses; Lens ... This pathway provides resources for understanding motion in one dimension. The fundamentals of vector and scalars are covered, and the key concepts of position, displacement, speed, velocity and acceleration are explained. The pathway concludes with a series of questions to test understanding of the topic. 6 Favorites.This pathway provides resources for understanding motion in one dimension. The fundamentals of vector and scalars are covered, and the key concepts of position, displacement, speed, velocity and acceleration are explained. The pathway concludes with a series of questions to test understanding of the topic. 6 Favorites. Three short virtual lab investigations. 1) Validating Snell's Law, 2) Describing the intensity of the reflected and refracted rays and 3) determining the refractive index of a mystery metal. Subject. Physics. Level. High School, Undergrad - Intro. Type. Guided Activity, Lab. Duration.This is Snell's law, also known as Descarte’s Law, or The Law of Refraction. When light passes from one medium to another, some of this light is reflected while another part penetrates into the medium with a change in its direction. These two phenomena are called the reflection and refraction of light. The angle of reflection of a ray of ...Launch Interactive. Learners are encouraged to open the Interactive and Explore. An activity sheet is not needed for this Interactive. Our Who Can See Who? simulation is now available with a Concept Checker. Do the simulation. Then follow it up with the Concept Checker. Learners and Instructors may be interested in viewing the accompanying ... oPhysics. Kinematics. Polarization of Light. Description. This is a simulation intended to help visualize polarization. A polarizing filter has a particular transmission axis and only allows light waves aligned with that axis to pass through. In this simulation unpolarized waves pass through a vertical slit, leaving only their vertical components. oPhysics. Kinematics. Polarization of Light. Description. This is a simulation intended to help visualize polarization. A polarizing filter has a particular transmission axis and only allows light waves aligned with that axis to pass through. In this simulation unpolarized waves pass through a vertical slit, leaving only their vertical components.oPhysics. Select a simulation from one of the above categories or click on a category to see descriptions of the simulations for that category. Hydrogen Energy Levels. This is a simulation of an atomic energy level diagram of the hydrogen atom.lack of medium) for light, 𝑣<𝑐 for anything that isn’t vacuum. This means that 𝑛>1, and the larger 𝑛 is, the slower light travels through the medium. In the third video, green laser light passes from air to a piece of acrylic. The index of refraction for the acrylic is 3) (1 point) Calculate the speed of light 𝑣 as it travelsRegular and Diffused Reflection. The light gets reflected from the surfaces. Any surface which is polished or in other words is shiny always acts like a mirror. The observation of light bouncing off the surfaces is termed reflection. The light after reflection travels in the same medium from where the ray was incident on the surface.S3P-2-07 Summarize the early evidence for Newton’s particle model of light. Include: propagation, reflection, refraction, dispersion S3P-2-08 Experiment to show the particle model of light predicts that the velocity of light in a refractive medium is greater than the velocity of light in an incident medium (vr > vi).Launch Interactive. Learners are encouraged to open the Interactive and Explore. An activity sheet is not needed for this Interactive. Our Who Can See Who? simulation is now available with a Concept Checker. Do the simulation. Then follow it up with the Concept Checker. Learners and Instructors may be interested in viewing the accompanying ... How does a lens or mirror form an image? See how light rays are refracted by a lens or reflected by a mirror. Observe how the image changes when you adjust the focal length of the lens, move the object, or move the screen.In this Interactive, learners can drag a candle to various positions in front of a curved mirror and quickly observe the characteristics of the images that are formed. It's that simple; no dripping candle wax, no mess to clean up, just pure physics. Now available with a Concept Checker. The manner in which light is reflected from a surface depends on the surface’s smoothness. Light that is reflected from a rough, textured surface, such as paper, cloth, or unpolished wood, is reflected in many different directions, as shown in Fig 1(a). This type of reflection is called diffuse reflection.Join photographer Nicholas on his expedition to Antarctica to photograph the wildlife. In this simulation, you will learn about the wave-like behaviors of light. When light travels from one medium into another, the rays can reflect off of the surface. Depending on the angle and the media, the light can also refract.Lay the mirror flat on the table with the shiny side up. Hold the flashlight at an angle pointing down toward the mirror. Explain to students that the light will be reflected off the mirror. Their task is to use the construction paper to catch the reflected light in order to pinpoint exactly where it goes.Ellipse Reflection Model. Move the points. Adjust number of segments. Press Play. This is a computer model of how sound (or light, etc) reflects inside an ellipse. Points "F" and "G" are the focus points of the ellipse. Example: Stand at one focus point in an elliptical room. A friend could stand at the other focus point and whisper: you would ... The Optics Bench Interactive is shown in the iFrame below. There is a small hot-spot in the lower-right corner of the iFrame. Dragging this hot-spot allows you to change the size of iFrame to whatever dimensions you prefer. Our Optics Bench simulation is now available with a Concept Checker that focuses on Concave Mirrors with this activity. Do ...White light is made up of light rays with different wavelengths which we see as various colors. When light refracts, the amount of bending depends upon the light's wavelength. It is maximum for violet and minimum for red. Hence white light splits into different colored rays, each with different amount of bending, when passing through a prism. In this video You will learn the basics of refraction of light. Here the concept of total internal reflection (TIR) and Critical Angle has also been discusse...Enhance productivity with 3DOptix, Optical design and Simulation software. Ray Optics describes light propagation in terms of “rays” and is commonly concerned with how light is propagated, reflected, and refracted and the formation of images. The “ray” in geometric optics is an abstraction, or “instrument”, which can be used to ...The angle between the reflected ray and the normal is known as the angle of reflection. (These two angles are labeled with the Greek letter "theta" accompanied by a subscript; read as "theta-i" for angle of incidence and "theta-r" for angle of reflection.) The law of reflection states that when a ray of light reflects off a surface, the angle ... This pathway provides resources for understanding motion in one dimension. The fundamentals of vector and scalars are covered, and the key concepts of position, displacement, speed, velocity and acceleration are explained. The pathway concludes with a series of questions to test understanding of the topic. 6 Favorites.Seen by observer. Simulate the rays and images seen from some position. The blue circle is the observer. Any rays crossing it are considered to be "observed". The observer do not know where the rays actually begin, but may think they begin at some point (s) if they intersect there. The rays are shown in blue, and the point (s) in orange.Polarized light waves are light waves in which the vibrations occur in a single plane. The process of transforming unpolarized light into polarized light is known as polarization. There are a variety of methods of polarizing light. The four methods discussed on this page are: Polarization by Transmission. The Plane Mirror Images Interactive is a skill-building tool that allows the user to explore the formation of images in plane mirrors. It makes a wonderful complement to lab activities on the law of reflection and the characteristics of plane mirror images. The Interactive takes a Tutorial approach to these topics. Jul 21, 2020 · In/Post-Class Activity, Bending Light, PhET. Description. This is a 60 to 90 min. worksheet related to the concept of refraction and reflection with conceptual questions and simulations activities. Students can observe, examine, explore and connect the simulations to the concepts and would have a better understanding of bending/refracting light ... 1 PHYS 304 LAB PhET Simulation: Reflection of Light In this activity students will be exploring reflection of light in a plane mirror using the “Bendin g Light ” PhET simulation. Open the simulation by clicking on the link: Learning Objectives By the end of this lab activity, students will be able to: • Explain what happens to light when ...In this video You will learn the basics of refraction of light. Here the concept of total internal reflection (TIR) and Critical Angle has also been discusse...Interactive is shown in the iFrame below. There is a small hot-spot in the lower-right corner of the iFrame. Dragging this hot-spot allows you to change the size of iFrame to whatever dimensions you prefer. Our Who Can See Who? simulation is now available with a Concept Checker. Do the simulation. Then follow it up with the Concept Checker. Our ...Bending Light Simulation Bend and Manipulate. Reflection and Refraction ... Details of Reflection and Refraction Demonstration Video. What is a Kaleidoscope? ...oPhysics. Select a simulation from one of the above categories or click on a category to see descriptions of the simulations for that category. Hydrogen Energy Levels. This is a simulation of an atomic energy level diagram of the hydrogen atom. Mar 3, 2021 · Regular and Diffused Reflection. The light gets reflected from the surfaces. Any surface which is polished or in other words is shiny always acts like a mirror. The observation of light bouncing off the surfaces is termed reflection. The light after reflection travels in the same medium from where the ray was incident on the surface. REFLECTION AND REFRACTION SIMULATION. The purpose of this activity is to study how light reflects off a shiny surface, and how it refracts when entering a transparent material. Submit your answers using Blackboard. The angle of incidence and reflection are labeled i and r respectively.Founded in 2002 by Nobel Laureate Carl Wieman, the PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations. PhET sims are based on extensive education <a {0}>research</a> and engage students through an intuitive, game-like environment where students learn through exploration and discovery.This is a simple simulation showing the reflection and refraction of a ray of light as it attempts to move from one medium to another. Use the sliders to adjust the index of refraction of each of the two materials, as well as the angle of incidence (the angle between the incident ray of light and the normal to the surface).In this Interactive, learners can drag a candle to various positions in front of a curved mirror and quickly observe the characteristics of the images that are formed. It's that simple; no dripping candle wax, no mess to clean up, just pure physics. Now available with a Concept Checker. The Optics Bench Interactive is shown in the iFrame below. There is a small hot-spot in the lower-right corner of the iFrame. Dragging this hot-spot allows you to change the size of iFrame to whatever dimensions you prefer. Our Optics Bench simulation is now available with a Concept Checker that focuses on Concave Mirrors with this activity. Do ...How does a lens or mirror form an image? See how light rays are refracted by a lens or reflected by a mirror. Observe how the image changes when you adjust the focal length of the lens, move the object, or move the screen.Reflection, refraction and diffraction are all boundary behaviors of waves associated with the bending of the path of a wave. The bending of the path is an observable behavior when the medium is a two- or three-dimensional medium. Reflection occurs when there is a bouncing off of a barrier. Reflection of waves off straight barriers follows the ... The Interactive consists of two parts. Part 1 is titled How do light rays reflect? This part introduces the law of reflection and addresses the manner in which light reflects off a plane mirror. Part 2 is titled How do images form in plane (flat) mirrors? This part investigates the interaction between light from the object and the observer's eye. Interactive is shown in the iFrame below. There is a small hot-spot in the lower-right corner of the iFrame. Dragging this hot-spot allows you to change the size of iFrame to whatever dimensions you prefer. Our Who Can See Who? simulation is now available with a Concept Checker. Do the simulation. Then follow it up with the Concept Checker. Our ...The phenomenon observed in this part of the lab is known as total internal reflection. Total internal reflection, or TIR as it is intimately called, is the reflection of the total amount of incident light at the boundary between two media. TIR is the topic of focus in Lesson 3. To understand total internal reflection, we will begin with a ... Total Internal Reflection. This 1.5-minute video features a demonstration in which a beam of light is directed into a hemicylindrical block of glass. The light approaches along the curved side of the cylinder along the radial line so that there is no refraction upon entering the block. Refraction occurs at the flat edge of the block. Bending Light 1.1.29 - PhET Interactive Simulations Description Simulation of image formation in concave and convex mirrors. Move the tip of the Object arrow or the point labeled focus. Move the arrow to the right side of the mirror to get a convex mirror.Apr 2, 2014 · Although light is an everyday phenomenon that we constantly observe, a numerous researches have reported that students often displayed learning difficulties and hold unscientific understanding on physics concepts of light wave. To address the situation, inquiry-based learning process with a support of computer simulation has been proved its benefits on development of student’s conceptual ... The angle between the reflected ray and the normal is known as the angle of reflection. (These two angles are labeled with the Greek letter "theta" accompanied by a subscript; read as "theta-i" for angle of incidence and "theta-r" for angle of reflection.) The law of reflection states that when a ray of light reflects off a surface, the angle ... Description. This is a visual simulation of the reflection of a wave pulse. Use the check boxes choose between a fixed end (bouncing off a more rigid medium) or a free end (bouncing off a less rigid medium). Use the other check boxes to show or hide the undisturbed incident and reflected waves, so that you can see how their superposition causes ... Explore bending of light between two media with different indices of refraction. See how changing from air to water to glass changes the bending angle. Play with prisms of different shapes and make rainbows.oPhysics. Select a simulation from one of the above categories or click on a category to see descriptions of the simulations for that category. Hydrogen Energy Levels. This is a simulation of an atomic energy level diagram of the hydrogen atom.Mar 3, 2021 · Regular and Diffused Reflection. The light gets reflected from the surfaces. Any surface which is polished or in other words is shiny always acts like a mirror. The observation of light bouncing off the surfaces is termed reflection. The light after reflection travels in the same medium from where the ray was incident on the surface. Sample Learning Goals. Explain how light bends at the interface between two media and what determines the angle. Apply Snell’s law to a laser beam incident on the interface between media. Describe how the speed and wavelength of light changes in different media. Describe the effect of changing wavelength on the angle of refraction.The subject of this chapter is the reflection and refraction of light—or electromagnetic waves in general—at surfaces. We have already discussed the laws of reflection and refraction in Chapters 26 and 33 of Volume I. Here’s what we found out there: The angle of reflection is equal to the angle of incidence.Polarized light waves are light waves in which the vibrations occur in a single plane. The process of transforming unpolarized light into polarized light is known as polarization. There are a variety of methods of polarizing light. The four methods discussed on this page are: Polarization by Transmission.The angle between the reflected ray and the normal is known as the angle of reflection. (These two angles are labeled with the Greek letter "theta" accompanied by a subscript; read as "theta-i" for angle of incidence and "theta-r" for angle of reflection.) The law of reflection states that when a ray of light reflects off a surface, the angle ... The lighting simulation software is primarily used in illumination design to simulate and optimize light pipes, and light guides, and non-imaging lenses and mirrors. TracePro is also a powerful tool for analysis of aspects of imaging systems such as stray light analysis and polarization effects. With its full set of features, designers can ...Reflection of light (and other forms of electromagnetic radiation) occurs when the waves encounter a surface or other boundary that does not absorb the energy of the radiation and bounces the waves away from the surface. This tutorial explores the incident and reflected angles of a single light wave impacting on a smooth surface.until the wave theory of light was proposed. It is now well understood and experimentally verified that light travels more slowly through materials than through empty space. Air is mostly empty space, so the slowing down of light in air is very small and can be ignored in many cases. The index of refraction of a material is defined as follows:until the wave theory of light was proposed. It is now well understood and experimentally verified that light travels more slowly through materials than through empty space. Air is mostly empty space, so the slowing down of light in air is very small and can be ignored in many cases. The index of refraction of a material is defined as follows:Description. Prism color dispersion, ala Pink Floyd. Move the white dot to change the orientation of the incident ray of white light. Use the sliders to adjust the index of refraction of the surrounding material (n1), the red light index of refraction of the prism (nred), and the percent difference between the index of refraction of the prism ...6.3.2: Refraction Simulation. The ratio of the speed of light in a material to the speed in a vacuum ( c = 3.0 ×108 m/s c = 3.0 × 10 8 m/s) is called the index of refraction; n = c/v n = c / v where v v is the speed of light in the medium. In this simulation we will investigate the effects of a change in the speed of a wave as it moves from ...Three short virtual lab investigations. 1) Validating Snell's Law, 2) Describing the intensity of the reflected and refracted rays and 3) determining the refractive index of a mystery metal. Subject. Physics. Level. High School, Undergrad - Intro. Type. Guided Activity, Lab. Duration.Light from the sun for example is composed of 7 distinct colors of light, and white light can be created with just three colors; blue, green and red light. Test your understanding and self-check Open the full B end i ng Li g ht simulation 6. Aug 13, 2020 · 6.3.2: Refraction Simulation. The ratio of the speed of light in a material to the speed in a vacuum ( c = 3.0 ×108 m/s c = 3.0 × 10 8 m/s) is called the index of refraction; n = c/v n = c / v where v v is the speed of light in the medium. In this simulation we will investigate the effects of a change in the speed of a wave as it moves from ... The light rays from an actual object bounce off the mirror to give a virtual image. With a flat mirror, the real object and the virtual object are symmetric and appear to be at the same distance on either side of the plane of the mirror. Symmetry rules at work in the reflection process explain how an image is formed by a plane mirror. Object A ... Reflection of light (and other forms of electromagnetic radiation) occurs when the waves encounter a surface or other boundary that does not absorb the energy of the radiation and bounces the waves away from the surface. The simplest example of visible light reflection is the surface of a smooth pool of water, where incident light is reflected ...Hi Students and Teachers! Here is a tutorial on how to run the Reflection and Refraction Simulation. I hope this is helpful. Remember: This is Fine and I Can...Founded in 2002 by Nobel Laureate Carl Wieman, the PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations. PhET sims are based on extensive education <a {0}>research</a> and engage students through an intuitive, game-like environment where students learn through exploration and discovery.The law of reflection states that the angle of reflection (θ r) equals the angle of incidence (θ i), θ r = θ i (1) The normal, incident ray and reflected ray all lie in the same plane (Fig. 1). In this lab, you will study the image formation by plane mirrors using an online simulation (Fig. 2 below). Fig. 1: Reflection of light from a ...
Welcome to Ray Optics Simulation. To add an optical component, select a tool and click the blank space. To load an example, please go to the Gallery page. File: Undo Redo Reset Save Open Export Get Link View Gallery. Tools: Ray Beam Point source Blockers Mirrors Glasses Ruler Protractor Detector Text Move view. View: . T mobile sm dp+ address
The Plane Mirror Images simulation blends an interactive Tutorial with an interactive simulation. Students will learn about the law of reflection and how it can be used to determine the location and characteristics of an image formed by a plane mirror.This is a simple simulation showing the reflection and refraction of a ray of light as it attempts to move from one medium to another. Use the sliders to adjust the index of refraction of each of the two materials, as well as the angle of incidence (the angle between the incident ray of light and the normal to the surface). Light from the sun for example is composed of 7 distinct colors of light, and white light can be created with just three colors; blue, green and red light. Test your understanding and self-check Open the full B end i ng Li g ht simulation 6. This is a simple simulation showing the reflection and refraction of a ray of light as it attempts to move from one medium to another. Use the sliders to adjust the index of refraction of each of the two materials, as well as the angle of incidence (the angle between the incident ray of light and the normal to the surface).Simulate the rays and images seen from some position. The blue circle is the observer. Any rays crossing it are considered to be "observed". The observer do not know where the rays actually begin, but may think they begin at some point (s) if they intersect there. The rays are shown in blue, and the point (s) in orange.The Interactive consists of two parts. Part 1 is titled How do light rays reflect? This part introduces the law of reflection and addresses the manner in which light reflects off a plane mirror. Part 2 is titled How do images form in plane (flat) mirrors? This part investigates the interaction between light from the object and the observer's eye. Optics Bench. The Optics Bench Interactive provides a virtual optics bench for exploring the images formed by mirrors and lenses. The height of the object (either a candle, an arrow or a set of letters) can be easily adjusted. The focal length of the mirror or lens can also be changed.How does a lens or mirror form an image? See how light rays are refracted by a lens or reflected by a mirror. Observe how the image changes when you adjust the focal length of the lens, move the object, or move the screen.This is a simple simulation showing the reflection and refraction of a ray of light as it attempts to move from one medium to another. Use the sliders to adjust the index of refraction of each of the two materials, as well as the angle of incidence (the angle between the incident ray of light and the normal to the surface). Sample Learning Goals. Explain how light bends at the interface between two media and what determines the angle. Apply Snell’s law to a laser beam incident on the interface between media. Describe how the speed and wavelength of light changes in different media. Describe the effect of changing wavelength on the angle of refraction.This experiment contains two parts to be done, which are: Part I:This part defines the reflection and refraction laws of light and use Snell’s law to calculate the index of refraction of unknown material. Part II: This part defines the meaning of the critical angle and the total internal reflection and use the critical angle to calculate the ...Join photographer Nicholas on his expedition to Antarctica to photograph the wildlife. In this simulation, you will learn about the wave-like behaviors of light. When light travels from one medium into another, the rays can reflect off of the surface. Depending on the angle and the media, the light can also refract. Seen by observer. Simulate the rays and images seen from some position. The blue circle is the observer. Any rays crossing it are considered to be "observed". The observer do not know where the rays actually begin, but may think they begin at some point (s) if they intersect there. The rays are shown in blue, and the point (s) in orange.This pathway provides resources for understanding motion in one dimension. The fundamentals of vector and scalars are covered, and the key concepts of position, displacement, speed, velocity and acceleration are explained. The pathway concludes with a series of questions to test understanding of the topic. 6 Favorites.This is a simple simulation showing the reflection and refraction of a ray of light as it attempts to move from one medium to another. Use the sliders to adjust the index of refraction of each of the two materials, as well as the angle of incidence (the angle between the incident ray of light and the normal to the surface)..