Reflection & Refraction – Curved Boundary
$0.00
The diagram shows an incident ray of light approaching the boundary between air and glass.
- When the ray strikes the boundary between air and glass some of the light bounces off the surface of the glass because it is highly reflective.
- The diagram demonstrates that the angle of incidence and angle of reflection are the same.
- The angles of incidence and reflection are both measured between the ray and the normal (the dotted green line).
Description
Reflection & Refraction - Curved Boundary
TRY SOME QUICK QUESTIONS AND ANSWERS TO GET STARTED
About the diagram
Have you already checked out An Introduction to Reflection, Refraction and Dispersion?
It is the opening page of our Reflection, Refraction and Dispersion Series and contains masses of useful information. This is the table of contents:
Overview of this page
- This page provides an introduction to a situation in which both reflection and refraction take place at a curved boundary between two transparent media.
- It looks at the path of white light rather than at the paths of the different wavelengths that white light contains.
- Related topics including dispersion are covered on other pages of this series.
- Introductions to the terms refractive index and the law of refraction (sometimes called Snell’s law) also appear on later pages in the series.
An overview of reflection
- Reflection takes place when incoming light strikes the surface of a medium and the light bounces off and returns into the medium from which it originated.
- Reflection takes place when light is neither absorbed by an opaque medium nor transmitted through a transparent medium.
An overview of refraction
- Refraction refers to the way that light (electromagnetic radiation) changes direction and speed as it travels from one transparent medium into another.
- Refraction takes place as light travels across the boundary between different transparent media and is a result of their different optical properties.
- When light is refracted its path bends and so changes direction.
- The effect of refraction on the path of a ray of light is measured by the difference between the angle of incidence and the angle of reflection.
- As light travels across the interface between different media (such as between air and glass) it changes speed.
- Depending on the media through which light is refracted, its speed can increase or decrease.
An overview of reflection and refraction
- When light strikes the boundary between two different media it may be partially reflected and partially refracted.
- If both reflection and refraction take place:
- A proportion of the light bounces off the surface of the new medium it encounters and returns into the medium from which it originated.
- A proportion crosses the boundary and undergoes refraction, so changes speed and direction.
The diagram
The diagram shows an incident ray of light approaching the curved boundary between air and glass.
- When the ray strikes the boundary between air and glass partial reflection and partial refraction takes place. This means that a proportion of the light bounces off the surface of the glass and returns into the air whilst the rest undergoes refraction.
- When incident light strikes a curved surface the normal is drawn at a tangent to the curve.
- In geometry, a tangent to a curve is a straight line that touches but does not intersect the curve at that point. It can be defined as a line through a pair of infinitely close points on a curve.
More about reflection
Reflection takes place when incoming light strikes the surface of a medium, some wavelengths are obstructed, and the wavefront bounces off and returns into the medium from which it originated.
- The laws of reflection are as follows:
- The incident ray, the reflected ray and the normal all lie in the same plane.
- The angle which the incident ray makes with the normal is equal to the angle which the reflected ray makes with the same normal.
- The reflected ray and the incident ray are on the opposite sides of the normal.
- Reflection takes place when light is neither absorbed by an opaque medium nor transmitted through a transparent medium.
Types of reflection
- When sunlight strikes window glass, some light is reflected and some is transmitted through the glass into the room beyond.
- The type of glass made for picture framing is designed to reflect some wavelengths and to transmit others.
- When light illuminates objects and then goes on to strike a mirror, the reflected image can be seen by an observer.
- A reflected image contains objects that we recognise and is made up of visible wavelengths of light and their corresponding colours.
- If a reflecting surface is very smooth, light waves remain in the same order as they bounce off the surface, producing a specular reflection.
- A diffuse reflection, in which no image is visible, results from light reflecting off a rough surface and light waves scattering in all directions.
- Reflection is independent of the optical density of the medium through which incident light travels or of the medium it bounces off.
More about refraction
- When light crosses the boundary between two different transparent media it undergoes refraction.
- The effect of refraction is that light changes speed along with its direction of travel.
- The result of the change in direction is that rays either bend towards or away from the normal.
- As the speed of light changes so does its wavelength but frequency and so the colour an observer sees remains the same.
- The normal is an imaginary line drawn on a ray diagram at right angles (perpendicular) to the boundary between two media.
- The change between the angle of incidence and the angle of refraction of a ray of light is always measured between the ray and the normal.
- Whether light bends towards or away from the normal depends on the difference in optical density of the new medium it encounters.
- An incident ray of light is refracted towards the normal and slows down when it travels from air into glass. Compared with air, glass is a slower, more optically dense medium (with the higher refractive index).
- An incident ray of light is refracted away from the normal and speeds up when it travels from glass into air. Compared with glass, air is a faster, less optically dense medium (with a lower refractive index).
Calculating the angle of refraction
- The direction in which a ray bends, and the precise angle, can be calculated if the type and refractive indices of both media are known.
- The effect of refraction can be calculated using a neat little equation called the law of refraction (also known as Snell’s law).
- If three of the variables are known, the law of refraction can be used to calculate the fourth.
- Tables of refractive indices are available for common materials so that the change in direction of a ray can be calculated.
- Tables of refractive indices for common materials often provide both the refractive index for white light as well as indices for specific wavelengths.
For an explanation of the refractive index (index of refraction) of a medium see: Refractive Index Explained.
For an explanation of how to use the refractive index of a medium see: How to Use the Refractive Index of a Medium.
For an explanation of the Law of Refraction see: Snell’s Law of Refraction Explained.
Some key terms
The angle of refraction measures the angle to which light bends as it passes across the boundary between different media.
- The angle of refraction is measured between a ray of light and an imaginary line called the normal.
- In optics, the normal is a line drawn on a ray diagram perpendicular to, so at a right angle to (900), the boundary between two media.
- See this diagram for an explanation: Refraction of a ray of light
- If the boundary between the media is curved, the normal is drawn perpendicular to the boundary.
The refractive index (index of refraction) of a medium measures how much the speed of light is reduced when it passes through a medium compared to its speed in a vacuum.
- Refractive index (or, index of refraction) is a measurement of how much the speed of light is reduced when it passes through a medium compared to the speed of light in a vacuum.
- The concept of refractive index applies to the full electromagnetic spectrum, from gamma-rays to radio waves.
- The refractive index can vary with the wavelength of the light being refracted. This phenomenon is called dispersion, and it is what causes white light to split into its constituent colours when it passes through a prism.
- The refractive index of a material can be affected by various factors such as temperature, pressure, and density.
If one line is normal to another, then it is at right angles. So in geometry, the normal is a line drawn perpendicular to and intersecting another line.
In optics, the normal is an imaginary line drawn on a ray diagram perpendicular to, so at a right angle to (900), to the boundary between two media.
- Expressed more formally, in optics, the normal is a geometric construct, a line drawn perpendicular to the interface between two media at the point of contact. This conceptually defined reference line is crucial for characterizing various light-matter interactions, such as reflection, refraction, and absorption.
- Light travels in a straight line through a vacuum or a transparent medium such as air, glass, or still water.
- If light encounters a force, an obstacle or interacts with an object, a variety of optical phenomena may take place including absorption, dispersion, diffraction, polarization, reflection, refraction, scattering or transmission.
- Optics treats light as a collection of rays that travel in straight lines and calculates the way in which they change direction (deviate) when encountering different optical phenomena.
- When the normal is drawn on a ray diagram, it provides a reference against which the amount of deviation of the ray can be shown.
- The normal is always drawn at right angles to a ray of incident light at the point where it arrives at the boundary with a transparent medium.
- Expressed more formally, in optics, the normal is a geometric construct, a line drawn perpendicular to the interface between two media at the point of contact. This conceptually defined reference line is crucial for characterizing various light-matter interactions, such as reflection, refraction, and absorption.
The speed (or velocity) of a light wave is a measurement of how far it travels in a certain time.
- The speed of light is measured in metres per second (m/s).
- Light travels through a vacuum at 300,000 kilometres per second.
- The exact speed at which light travels through a vacuum is 299,792,458 metres per second.
- Light travels through other media at lower speeds.
- A vacuum is a region of space that contains no matter.
- Matter is anything that has mass and occupies space by having volume.
- When discussing electromagnetic radiation the term medium (plural media) is used to refer to anything through which light propagates including empty space and any material that occupies space such as a solid, liquid or gas.
- In other contexts empty space is not considered to be a medium because it does not contain matter.
The angle of incidence measures the angle at which incoming light strikes a surface.
- The angle of incidence is measured between a ray of incoming light and an imaginary line called the normal.
- See this diagram for an explanation: Reflection of a ray of light
- In optics, the normal is a line drawn on a ray diagram perpendicular to, so at a right angle to (900), the boundary between two media.
- If the boundary between the media is curved, then the normal is drawn at a tangent to the boundary.
Incident light refers to light that is travelling towards an object or medium.
- Incident light refers to light that is travelling towards an object or medium.
- Incident light may come from the Sun, an artificial source or may have already been reflected off another surface, such as a mirror.
- When incident light strikes a surface or object, it may be absorbed, reflected, refracted, transmitted or undergo any combination of these optical effects.
- Incident light is typically represented on a ray diagram as a straight line with an arrow to indicate its direction of propagation.
The angle of reflection measures the angle at which reflected light bounces off a surface.
- The angle of reflection is measured between a ray of light which has been reflected off a surface and an imaginary line called the normal.
- See this diagram for an explanation: Reflection of a ray of light
- In optics, the normal is a line drawn on a ray diagram perpendicular to, so at a right angle to (900), the boundary between two media.
- If the boundary between the media is curved then the normal is drawn perpendicular to the boundary.
A tangent to a circle is a straight line that touches but does not intersect the circle and is at right angles to a radial line drawn from the centre of the circle.
- In geometry, a tangent (or tangent line) to a curve is a straight line that touches but does not intersect the curve. It can be defined as a line through a pair of infinitely close points on a curve.
https://en.wikipedia.org/wiki/Tangent
The refractive index of a medium is the amount by which the speed (and wavelength) of electromagnetic radiation (light) is reduced compared with the speed of light in a vacuum.
- Refractive index (or, index of refraction) is a measure of how much slower light travels through any given medium than through a vacuum.
- The concept of refractive index applies to the full electromagnetic spectrum, from gamma-rays to radio waves.
- The refractive index of a medium is a numerical value and is represented by the symbol n.
- Because it is a ratio of the speed of light in a vacuum to the speed of light in a medium there is no unit for refractive index.
- If the speed of light in a vacuum = 1. Then the ratio is 1:1.
- The refractive index of water is 1.333, meaning that light travels 1.333 times slower in water than in a vacuum. The ratio is therefore 1:1.333.
- As light undergoes refraction its wavelength changes as its speed changes.
- As light undergoes refraction its frequency remains the same.
- The energy transported by light is not affected by refraction or the refractive index of a medium.
- The colour of refracted light perceived by a human observer does not change during refraction because the frequency of light and the amount of energy transported remain the same.
Diagrams are free to download
Downloads: Slides or Illustrations
DOWNLOAD DIAGRAMS
- SLIDES are optimized for viewing on-screen.
- ILLUSTRATIONS are optimized for printing on A4 pages in portrait format.
SLIDES
- Slides are available in JPG and AI (Adobe Illustrator) file formats.
- Titles: Slides have titles.
- Backgrounds: Black.
- Size: 1686 x 1124 pixels (3:2 aspect ratio).
ILLUSTRATIONS
- Illustrations are available in JPG and AI two file formats.
- Titles: No titles.
- Backgrounds: White.
- Size: 1686 x 1124 (3:2 aspect ratio). So all illustrations reproduce at the same scale when inserted into Word documents etc.
- Labels: Calibri 24pt Italic.
File formats: JPG & AI
DOWNLOAD THE DIAGRAM ON THIS PAGE AS A JPG FILE
- JPG (JPEG) diagrams are 1686 x 1124 pixels (3:2 aspect ratio).
- If a JPG diagram doesn’t fit your needs, you can download it as an AI (Adobe Illustrator) file and edit it yourself.
- JPG files can be placed or pasted directly into MS Office documents.
DOWNLOAD THE DIAGRAM ON THIS PAGE AS AN AI file
- All AI (Adobe Illustrator) diagrams are 1686 x 1124 pixels (3:2 aspect ratio).
- All our diagrams are created in Adobe Illustrator as vector drawings.
- Save as or export AI files to other formats including PDF (.pdf), PNG (.png), JPG (.jpeg) and SVG(.svg) etc.
Spelling: UK & US
We use English (UK) spelling by default here at lightcolourvision.org.
COPY & PASTING TEXT
- After copy/pasting text please do a spell-check to change our spelling to match your own document.
DOWNLOAD DIAGRAMS
- Download AI versions of diagrams to change the spelling or language used for titles, labels etc.
- We are adding American English (US) versions of diagrams on request. Just contact us and let us know what you need.
- When downloading JPG versions of diagrams, look out for JPG (UK) or JPG (US) in the download dialogue box.
Download agreement
DOWNLOAD AGREEMENT
Light, Colour, Vision & How To See More (https://lightcolourvision.org) : Copyright © 2015-2022 : MediaStudies Trust.
Unless stated otherwise the author of all images and written content on lightcolourvision.org is Ric Mann.
ALL RIGHTS RESERVED
No part of this website may be copied, displayed, extracted, reproduced, utilised, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical or otherwise including but not limited to photocopying, recording, or scanning without the prior written permission of MediaStudies Trust.
EXCEPTIONS
Exceptions to the above statement are made for personal, educational and non-profit purposes:
Before downloading, cutting and pasting or reproducing any information, images or other assets found on lightcolourvision.org we ask you to agree to the following terms:
- All information, images and other assets displayed and made available for download on the lightcolourvision.org website are copyright. This means there are limitations on how they can be used.
- All information, images and other assets displayed or made available for download are solely and exclusively to be used for personal, educational and non-profit purposes.
- When you find the resources you need, then part of the download process involves you (the user) ticking a box to let us (at lightcolourvision.org) know we both agree on how the material can be used.
- Please contact [email protected] before considering any use not covered by the terms of the agreement above.
The copyright to all information, images and all other assets (unless otherwise stated) belongs to:
The Trustees. MediaStudies Trust
111 Lynbrooke Avenue
Blockhouse Bay
Auckland 0600
New Zealand
[email protected]
We love feedback
Your name and email address will be used solely to provide you with information you have specifically requested. See our privacy policy at https://lightcolourvision.org/privacy/.
We welcome your feedback 🙂