IQ4) What are Electromagnetic Waves?
Mobile phones use a type of ELECTROMAGNETIC wave called "microwaves" to send information to other mobile phones without the need for connecting wires. So what are electromagnetic waves.
Electromagnetic energy travels in waves and spans a broad spectrum from very long radio waves to very short gamma rays. The human eye can only detect only a small portion of this spectrum called visible light. A radio detects a different portion of the spectrum, and an x-ray machine uses yet another portion. NASA's scientific instruments use the full range of the electromagnetic spectrum to study the Earth, the solar system, and the universe beyond.
When you tune your radio, watch TV, send a text message, or pop popcorn in a microwave oven, you are using electromagnetic energy. You depend on this energy every hour of every day. Without it, the world you know could not exist. Nasa Website on The Electromagnetic Spectrum |
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IQ5) How can light cause reflections, rainbows, sight and colours?
In this final episode Professor Brian Cox travels to Iceland, where the delicate splendour of a moonbow reveals the colours that paint our world, and he visits a volcano to explain why the sun shines. By exploring how sunlight transforms the plains of the Serengeti, drives the annual migration of humpback whales to the Caribbean and paints the moon red during a lunar eclipse, Brian reveals the colour signature of our life-supporting planet.
Finally, at an observatory high in the Swiss Alps, he shows how these colours aren't simply beautiful, but that understanding how they're created is allowing us to search for other Earths far out in the cosmos. |
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1.9) Light can be TRANSMITTED, SCATTERED and ABSORBED
1.10) Light can be REFLECTED
1.11) Light can be REFRACTED
Refractive Index, n - Write these notes in your exercise book
An important concept in refraction is the refractive index which gives an indication of the density of the medium. The higher the value of refractive index, n, the more dense the medium is. Also *the refractive index of a vacuum or air = 1 •the more dense mediums like glass have numbers higher than 1 such as glass is about 1.6 •It also means that the higher the value of refractive index, the slower the speed of light |
Activities on Refraction - Complete worksheet 4.3) Refraction
Extension Activity - Applying Snell's Law
Answers
Extension Activity - Applying Snell's Law
Answers
1.12) Sight and Refraction
At the moment you are reading. Your eyes are open. They must be open. Otherwise, you could not see this page- or anything else.
The eyes are sense organs. They are the organs that allow us to see. The eyes receive and focus light. The light messages then go to the brain. The brain tells us what the light means. It tells us what we are seeing. And scientists see sight as an amazing application of refraction. Currently we are unable to make any camera or video device that can work as effectively as your eyes.
At the moment you are reading. Your eyes are open. They must be open. Otherwise, you could not see this page- or anything else.
The eyes are sense organs. They are the organs that allow us to see. The eyes receive and focus light. The light messages then go to the brain. The brain tells us what the light means. It tells us what we are seeing. And scientists see sight as an amazing application of refraction. Currently we are unable to make any camera or video device that can work as effectively as your eyes.
Activity 1) Dissection of a Cow's Eye - watch the video to get detailed information about the different parts of the eye
Activity 2) Learn the function of the following parts of the eye - cornea, aqueous humour, iris, lens, vitreous humour, retina and optic nerve
i) Paste the diagram of the eye in your exercise books
ii) Create a table with each of the parts provided above and write their function using the following website BBC Bitesize "The EYE"
iii) Identify the four parts of the eye that cause refraction AND which one refracts light the most
i) Paste the diagram of the eye in your exercise books
ii) Create a table with each of the parts provided above and write their function using the following website BBC Bitesize "The EYE"
iii) Identify the four parts of the eye that cause refraction AND which one refracts light the most
Activity 3) Find Your Blind Spot
* Look at the figure of a cross and the dot below
* Place your hand over your left eye and look at the CROSS only with your right eye
* Move closer or further from the diagram until the dot disappears. This is the point where you have the blind spot in your right eye
* Repeat this test but this time with your right eye closed and your left eye open
* Why do we have a blind spot?????
* Look at the figure of a cross and the dot below
* Place your hand over your left eye and look at the CROSS only with your right eye
* Move closer or further from the diagram until the dot disappears. This is the point where you have the blind spot in your right eye
* Repeat this test but this time with your right eye closed and your left eye open
* Why do we have a blind spot?????
An interesting fact about our eyesight is that the image of the object that we are looking at is formed on the retina upside down.
So why don't we see everything upside down???? Our brain turns the image the right way up. There are some people whose brains do not do this for them. Imagine how confusing that would be???? |
1.13) Glasses and Refraction
Activity A) How do we see things close and then far? - draw these diagrams in your exercise book and write a paragraph that explains how the eye focusses on distant and near objects.
Activity B) How do glasses work?
Short-sightedness and long-sightedness are conditions in which a sharp image of the object is not formed on the retina. Copy these diagrams and include a sentence that explains what the lens is doing and where the image is forming for each condition
Draw diagrams to show the correct lens can be used to improve the eyesight of someone who is
i) short-sighted
ii) long-sighted
i) short-sighted
ii) long-sighted
Activity C) How does our eyes detect COLOUR and BLACK/WHITE?
The retina is at the back part of the eye. It is made up of two kinds of nerve cells: rods and cones
- Rods are sensitive to brightness hence black, white and shades of grey
- Cones are sensitive to colour. Without cones we would not see colour. There are three types of cones - blue, green and red. Hence there is one cone for each primary colour of light.
- Rods are sensitive to brightness hence black, white and shades of grey
- Cones are sensitive to colour. Without cones we would not see colour. There are three types of cones - blue, green and red. Hence there is one cone for each primary colour of light.
The image below is of an electron microscope image of rods and cones
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This image shows the structure of the Retina
Hank takes us on a tour of your EYE and VISION. With a little help from an optical illusion, we take a look inside your eyes to try to figure out how your sense of vision works -- and how it can be tricked. Watch this video and make notes about how we actually see the world around us |
Optional Activity) You can try the test for Colour Blindness
Optional Activity) What can we tell about our health by looking at our eyes?
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Your eyes are tiny spheres of wonder. A doctor can find warning signs of high blood pressure, diabetes, and a whole range of other systemic health issues, just by examining your eyes. Ophthalmologist Neal Adams explains why the eye's tissues and blood vessels make such a good barometer for wellness.
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Amazing Video) The Boy who sees without eyes!!
A documentary about Ben Underwood, a boy who has taught himself to use echo location to navigate around the world. Ben Underwood is blind, but has managed to do some truly extraordinary feats.
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Optional Activity) Optical Illusions show how we see!!
Beau Lotto's colour games puzzle your vision, but they also spotlight what you can't normally see: how your brain works. This fun, first-hand look at your own versatile sense of sight reveals how evolution tints your perception of what's really out there. Watch this amazing video
Beau Lotto's colour games puzzle your vision, but they also spotlight what you can't normally see: how your brain works. This fun, first-hand look at your own versatile sense of sight reveals how evolution tints your perception of what's really out there. Watch this amazing video
1.14) Rainbows and Blue Skies
Question 1) How are RAINBOWS formed?
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Question 2) Why is the Sun Yellow and the Sky Blue?
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1.15) Colour and LIght
What is colour? What is it that determines the colour of an object? And what the heck is refraction? Good thing we just learned about electromagnetic radiation! Especially the visible spectrum. Let's take a look.
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