Science Interactive LTD Multimedia CD-ROM for PC is a collection of 38 units totalling over 1150 PowerPoint slides matched to current single and double Science GCSE syllabuses. Each unit covers a wide range of different delivery and learning styles, offering an exciting way to involve your pupils during lessons or revision sessions. All styles of teaching and learning are supported through use of high quality images, graphics, challenging exercises and questions. Units can be used in the classroom via an interactive whiteboard , data projector or used during individual study via a PC or school network. Full users’ licence is available under our ‘ comprehensive package ’ or lessons can be purchased separately. Science Interactive LTD. PO BOX 50764 LONDON NW6 9AT email: sales@science-interactive.co.uk web: www:science-interactive.co.uk GCSE SCIENCE OCR EDEXCEL AQA Science Interactive LTD Copyright 2005 Unit 19: The Transitional Metals Unit 18: Metals and their Properties Unit 17: The Alkali Metals Unit 16: The Periodic Table and its Elements Unit 15: Genetic Engineering Unit 14: Evolution and Human Impact Unit 13: Inheritance and Selection Unit 12: Mitosis and Meiosis Unit 11: Flow of Energy and Elements through the Environment Unit 10: Water Transport in Plants Unit 9: Photosynthesis in Green Plants Unit 8: Drugs and Bad Body Maintenance Unit 7: Hormones and the Endocrine System Unit 6: Human Homeostasis Unit 5: Nervous System and the Senses Unit 4: The Respiratory System Unit 3: Healthy Body and Immunity Unit 2: The Circulatory System Unit 1: The Digestive System Unit 38: Cells, Tissue, Organs and Organs systems Unit 37: Natural Forces Unit 36: Sound and Hearing Unit 35: The Alkaline Earth Metals Unit 34: The Earth and Plate Tectonics Unit 33: Earth and Space Unit 32: Newton's Forces and the Effects of Forces Unit 31: Radioactivity Unit 30: Light and the Electromagnetic Spectrum Unit 29: Electricity Unit 28: Generating Electricity and its Domestic Use Unit 27: Energy Unit 26: Rates of Reaction Unit 25: The Noble Gases, their Properties and Uses Unit 24: The Halogens, their Uses and Compounds Unit 23: Ionic and Covalent Compounds Unit 22: Elements, Molecules and Compounds Unit 21: Rock Cycle Unit 20: Crude Oil and its Products

Unit 30 Light and the Electromagnetic Spectrum Science Interactive LTD Copyright 2005 (LW) (MW) (VHF) radio waves (UHF) microwaves Infra red light Ultra - Violet X - rays Gamma 10 3 m 10 2 m 10 1 m 1m 10 - 1 m 10 - 2 m 10 - 4 m 10 - 6 m 10 - 8 m 10 - 10 m 10 - 12 m

Unit 30

Light and the Electromagnetic Spectrum

That visible light is just a small part of the much larger electromagnetic spectrum. That the electromagnetic spectrum is a collection of waves with similar properties. That these waves have different uses based on their individual properties. That the speed of light can be calculated using Michelson’s experiment. That visible white light is a collection of the seven colours of the spectrum. That visible light can either be reflected or refracted. Some of the examples of devices that rely on reflection or refraction of visible light. That visible light can be totally internally reflected, for example in optic fibres. The similarities between the human eye and a camera. How the human eye forms an image. Electromagnetic, Spectrum, Radio waves, Ultrasound, Microwaves, Infra red, Visible, Light, Ultraviolet, X rays, Gamma rays, Radiation, Speed, Reflection, Refraction, Wavelength, Rainbow, Eye, Lens, Retina, Cornea, Optic & Image. Unit 30: Light and the Electromagnetic Spectrum web: www.science-interactive.co.uk email: sales@science-interactive.co.uk Science Interactive LTD PO BOX 50764 LONDON NW6 9AT Click mouse to begin Science Interactive LTD Copyright 2005 Understand: Keywords:

That visible light is just a small part of the much larger electromagnetic spectrum.

That the electromagnetic spectrum is a collection of waves with similar properties.

That these waves have different uses based on their individual properties.

That the speed of light can be calculated using Michelson’s experiment.

That visible white light is a collection of the seven colours of the spectrum.

That visible light can either be reflected or refracted.

Some of the examples of devices that rely on reflection or refraction of visible light.

That visible light can be totally internally reflected, for example in optic fibres.

The similarities between the human eye and a camera.

How the human eye forms an image.

Refraction of light two Light travels through a vacuum at 300,000 kms -1 . Through glass it travels more slowly, about two thirds the speed. The refractive index is calculated using the ratio of the two speeds. Refractive index = Speed of light in air Speed of light in substance Science Interactive LTD Copyright 2005 Glass Plastic Water 38.2 o 40.5 o 34.5 o Real position Virtual image Observer 200,000 1.5 Glass 120,000 2.4 Diamond 300,000 1.0 Air 225,000 1.33 Water Speed of light (kms -1 ) Refractive index Substance Equation Light rays travelling from air to glass slows down and are bent towards the normal. Light rays travelling from glass to air speed up and are bent away from the normal. The normal is at right angles to the media interface. The incoming and outgoing light rays are both parallel. If you are trying to hunt fish with a spear, you have to allow for refraction. This is because of the effects of light changing speed when leaving water to air. Where would you aim the spear ? Notes Diagram Refraction of light through water Refraction through different materials

Refraction of light three Lenses found in optical equipment including cameras, telescopes and even the human eye are able refract or b_______ light. Only c__________ lens are able to form a sharp virtual image. Images can be magnified larger than the actual object or diminished smaller than the object, depending on the type of lens that you use. Devices that use convex lenses include microscopes, zoom camera lenses and vision glasses. Names three other devices that use convex lenses ? Lenses and refraction of light: Science Interactive LTD Copyright 2005 Word bank: bend convex The stronger the convex lens, the larger the image. Look at the picture above, which eyesight condition is corrected by glasses with convex lenses ? A convex lens converges the light rays. The distance between the lens and the focal point is called the focal length. This distance depends on the strength of the lens. The image produced using a convex lens is virtual, smaller and upside down. The focal point is produced by the lens slowing down and refracting the light. Notes Convex lens three Diagram Convex lens one Convex lens two

Refraction of light four Lenses found in optical equipment including cameras, telescopes and glasses are made from plastic or even glass. Modern lenses are normally made from p________ rather than more traditional glass. Although plastics lenses are thicker, because of their lower refractive index, they are unbreakable. Concave or diverging lenses are unable to form a s_______ focused image. A concave lens bends the light rays away form an imaginary focal point that is behind the lens. Devices that use concave lenses include, wide angle camera lenses and vision glasses. Lenses and refraction of light: Science Interactive LTD Copyright 2005 Word bank: plastic sharp The stronger the concave lens the smaller the image. Look at the picture above, which eyesight condition is corrected by glasses with concave lenses ? A concave lens diverges the light rays. The distance between the lens and the focal point is called the focal length. This distance depends on the strength of the lens. The image produced using a concave lens is virtual, larger and the right way up. The focal point is produced by the lens slowing down and refracting the light. Notes Concave lens three Diagram Concave lens one Concave lens two

Total internal reflection one When light strikes the boundary between a medium with a very high refractive index and another with a very low refractive index, the light is totally r_________, remaining inside the medium. ‘ This is called total internal reflection.’ For example, an optic fibre or a doctors endoscope used during key hole s_______ exploits this effect, where the light is trapped inside the fibre. A diamond traps light, giving a diamond its ‘ fire ’ and ‘ brilliance .’ Total internal reflection: Science Interactive LTD Copyright 2005 Word bank: reflected surgery Even in water, light is trapped and seems to flows within the water to give this effect seen at night when the fountain is lit. Optic fibres are used to carry mainly electronic information across the world wide web. Its is very fast and known as broadband. Light appears to be trapped giving this diamond its characteristic ‘fire’ and ‘brilliance.’ Flawless diamonds have the best clarity. Light rays are reflected off the internal walls of the optic fibre. The advantage here is that it can change direction inside the cable. Notes Optic fibres Fountains Diagram Internal reflection Diamond

Total internal reflection two Most of the internet traffic is now carried from website server to your computer using broadband with ‘download speeds’ of up to 8 mbs per second . Information use to be carried by c_______ cable with download speeds of only 56 kbs per second. Light optic fibres have now transformed using the internet making it super fast. Light, as we know travels in glass around 200,000 kms -1 , meaning that inside a optic cable, it will take less that a tenth of one second to travel from England to Australia and back again. Using light to carry information: Science Interactive LTD Copyright 2005 Word bank: copper Doctors use endoscopes to examine areas inside the body. Why does using an endoscope decrease recovery time and reduce risk during surgery ? There are now millions of kilometres of optic fibres underground that are able to carry information from computer to computer via the world wide web. When light strikes the boundary between a medium with a very high refractive index and another with a very low refractive index, the light is totally reflected. This is called total internal reflection. Notes Endoscopes Diagram Total internal reflection Optic fibres

Eyesight the eye The eye allows c_______ and light vision so that you make sense of your environment and your place in it. The eye relies on a number of specialised cells and tissues to focus a light image, determine its c_______ and send this image to the brain. Why does having two eyes give you better perception of your environment and the distance between objects ? The human eye: Science Interactive LTD Copyright 2005 Word bank: colour retina Optic nerve Fovea Retina Vitreous humour Aqueous humour Lens Iris Pupil Cornea Tissue Optic nerve: carries information to the brain. Helps see objects in close detail. Helps keep shape of the eyeball. Contains all rod and cone cells to detect light and c_______. Helps keep shape of lens. Focuses light image onto r________. Controls the amount of light entering the eye. Allows light through the eye. Protects the lens and begins to focus Light rays. Function (complete table)

Eyesight forming an image one The human eye is our link to the outside World conveying millions of images every year that allow us to understand and manipulate our own e___________. A large part of the brain is dedicated to understanding the images collected and sent by our eyes to the brain via the optic nerve . The eye is like a simple c_______ with a lens that focuses an image. Both cameras and eyes are able to control the amount of light that falls on the film or retina. The image formed by both the eye and the camera are the same: The image is upside down, smaller and also virtual ! Forming an image: Science Interactive LTD Copyright 2005 Word bank: environment camera The camera forms an image which is upside down, smaller than the real object and virtual. This image is captured using photographic film. Camera Eye Picture Diagram The eye forms an image which is upside down, smaller than the real object and virtual. This image is sent to the brain via the optic nerve. Notes

Eyesight forming an image two Although most of the bending of light rays is done by the curved cornea, the lens focuses the object’s rays, forming a sharp image on the eye’s r_______. The shape of the lens is controlled by the ciliary muscles and the suspensory ligaments. Light is first bent by the c________, then by the clear l______. The image is focussed, inverted onto the r______, where the rod and cone cells detect light and colour. These cells convert the image into e___________ impulses which are sent via the o_____ nerve to the brain. The brain interprets this image according to your experiences. It also corrects the image so it is no longer upside down ! Forming an image: Science Interactive LTD Copyright 2005 Word bank: retina cornea lens electrical optic The ciliary body contracts when your eye focuses a near object. The lens is therefore allowed to form a fat shape. The ciliary body relaxes when your eye focuses a distant object. The lens is therefore pulled into a thin shape. Ciliary muscle Suspensory ligaments are allowed loose by the contracted ciliary muscles. This allows the lens to form a fat shape so that it can focus a near object like a book. Lens is fat, because rays from near objects need to be bent more to form a sharp image on the surface of the eye’s retina. Near object Distant object Diagram Lens is thin, because the rays from distant objects need to be bent less to form a sharp image on the surface of the eye’s retina. Lens Suspensory ligaments are pulled tight by the relaxed ciliary muscle. This pulls the lens into a thin shape so that the lens can focus a distant object like a stop sign. Suspensory ligaments

Eyesight Correcting sight The image that is formed on the eye’s retina, needs to be sharp and is f___________ by the lens. In many people, the lens is unable to form a sharp image. In longsighted people, the lens is too weak and the focal point falls behind the retina. Longsighted people require glasses that use convex lenses. In short-sighted people, the lens is too s________, forming an image which is in front of the retina. Short-sighted people need to wear glasses with concave lenses. Do contact lenses work in the same way ? Correcting eyesight: Short sighted Long sighted Concave lens Convex lens Science Interactive LTD Copyright 2005 Word bank: focussed strong People wear glasses to correct faults in their eyesight. A pair of glasses help us to produce a focused image on the eyes retina. Without glasses, life would be much more difficult ! Notes Short sighted Diagram 20/20 vision Normal vision Long sighted

1: Define the following terms: Electromagnetic spectrum, Radio waves, Ultrasound, Microwaves, Infra red, Visible light, Reflection, Refraction, Wavelength, Total internal reflection. 2: Look at the three diagram. Complete the table. 3: Answer the following: b) Give the full order of the electromagnetic spectrum starting with Gamma rays. Illustrate your answers with a diagram. Also give three properties of all electromagnetic waves. c) Give two examples of waves of the electromagnetic spectrum that can carry information. d) How do optic fibres carry information and explain total internal refraction. Use a diagram. e) Give one use for UV light and X-rays. Illustrate your answer with a diagram. f) Name an electromagnetic wave that can (i) Pass through metals (ii) Can cause a suntan (iii) Is used for radar (iv) Is emitted by warm objects (v) Is used by the human eye to see colour (vi) Is diffracted off buildings. Extension questions and homework Science Interactive LTD Copyright 2005 Total internal Reflection Reflection Three Two One Other examples Refraction Diagram

4: Complete the table: 5: a) Using radar apparatus, the wave echo takes 0.0002 seconds to travel from the source to the plane and back. Remembering that the speed of light is 300,000 kms -1 , how far away is the plane. b) What is the difference between a convex and a concave lens. Give an example of one device that uses (i) concave and (ii) convex reflectors. c) Light rays from the Sun takes approximately 8.7 minutes to travel from the Sun to Earth. Work out the distance in km between the two objects. d) What colour would a blue book look under (i) White light (ii) Blue light (iii) Green light (iv) Red light. 6: Ultraviolet, Gamma rays and radio rays are all part of the electromagnetic spectrum. Write down: a) Which has the longest wave length. b) Which has the highest frequency. c) Which is emitted by the nucleus of an atom. d) Two properties that they have in common 7: Complete the following: The full order of the electromagnetic spectrum is .__________________. The section with the longest wavelength is __________________. The waves that pass through metal are ________________ and those that damage your skin DNA causing cancer are _________________. Internet: Go to google.co.uk and find about how telescopes function, how they magnify distant images. Also find out about the use of optic fibres for communication and Broadband internet. Science Interactive LTD Copyright 2005 Red + Green Blue + Green Blue + Yellow Appearance Red + Blue Red + Green + Blue Colours of light added together