Wavelength & Speed of Light
$0.00
This diagram shows the waveform of rays of red light (electromagnetic radiation) travelling through equally sized blocks of different transparent materials.
- The top block contains a vacuum so the speed of light, the wavelength and the distance travelled are all shown to be 100%.
- The diagram then illustrates the relative speed, wavelength and distance travelled as light passes through each of the other materials.
- The speed of light in a vacuum is 299,792 kilometres per second. Different media reduce that speed by different amounts depending on their optical density.
- Optically rare medium (air) = a faster medium = smaller index of refraction.
- Optically dense medium (glass) = a slower medium = larger index of refraction.
- Notice that whilst the speed, wavelength and the distance travelled is different for each material, the frequency of the wave remains the same.
- Remember that frequency involves counting the frequency with which oscillations of a wave pass a given point in a given amount of time.
- In this diagram, there are seven wave-cycles in each case before each wave reaches the yellow line. The yellow line indicates the distance the light travels in each case over the same period of time. So the frequency is seven in every case.
Description
Wavelength & Speed of Light
TRY SOME QUICK QUESTIONS AND ANSWERS TO GET STARTED
300,000 kilometres per second.
A light wave in a vacuum travels at 300,000 kilometres (km) per second! Or to be exact, 299,792 km/sec.
Yes! The wavelength and speed at which light travels change as they travel through different media but frequency remains the same.
About the diagram
About the diagram
- This diagram shows the waveform of rays of red light (electromagnetic radiation) travelling through equally sized blocks of different transparent materials.
- The top block contains a vacuum so the speed of light, the wavelength and the distance travelled are all shown to be 100%.
- The diagram then illustrates the relative speed, wavelength and distance travelled as light passes through each of the other materials.
- The speed of light in a vacuum is 299,792 kilometres per second. Different media reduce that speed by different amounts depending on their optical density.
- Optically rare medium (air) = a faster medium = smaller index of refraction.
- Optically dense medium (glass) = a slower medium = larger index of refraction.
- Notice that whilst the speed, wavelength and distance travelled is different for each material, the frequency of the wave remains the same.
- Remember that frequency involves counting the frequency with which oscillations of a wave pass a given point in a given amount of time.
- In this diagram, there are seven wave-cycles in each case before each wave reaches the yellow line. The yellow line indicates the distance the light travels in each case over the same period of time. So the frequency is seven in every case.
Understanding the diagram:
- The speed, wavelength and distance travelled by the wave decreases as it passes through the list of materials because the optical density (and so the index of refraction) of each material is progressively increasing.
- Although the speed, wavelength and distance travelled by the wave decreases as it passes through each material, the number of waves generated over the same period of time remains the same.
- Because the frequency remains constant the colour of the ray remains the same.
Some key terms
Frequency
The frequency of electromagnetic radiation (light) refers to the number of wave-cycles of an electromagnetic wave that pass a given ...
Medium
Any material through which an electromagnetic wave propagates (travels) is called a medium (plural media). In optics, a medium is ...
Electromagnetic spectrum
The electromagnetic spectrum includes electromagnetic waves with all possible wavelengths of electromagnetic radiation, ranging from low energy radio waves through ...
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 🙂
