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1. Slide 1: Science Interactive LTD Copyright 2005 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 Unit 1: The Digestive System Unit 20: Crude Oil and its Products Unit 2: The Circulatory System Unit 21: Rock Cycle OCR Unit 3: Healthy Body and Immunity Unit 22: Elements, Molecules and Compounds EDEXCEL AQA Unit 4: The Respiratory System Unit 23: Ionic and Covalent Compounds Unit 5: Nervous System and the Senses Unit 24: The Halogens, their Uses and Compounds Unit 6: Human Homeostasis Unit 25: The Noble Gases, their Properties and Uses Unit 7: Hormones and the Endocrine System Unit 26: Rates of Reaction Unit 8: Drugs and Bad Body Maintenance Unit 27: Energy Unit 9: Photosynthesis in Green Plants Unit 28: Generating Electricity and its Domestic Use Unit 10: Water Transport in Plants Unit 29: Electricity Unit 11: Flow of Energy and Elements through the Environment Unit 30: Light and the Electromagnetic Spectrum Unit 12: Mitosis and Meiosis Unit 31: Radioactivity Unit 13: Inheritance and Selection Unit 32: Newton's Forces and the Effects of Forces Unit 14: Evolution and Human Impact Unit 33: Earth and Space Unit 15: Genetic Engineering Unit 34: The Earth and Plate Tectonics Unit 16: The Periodic Table and its Elements Unit 35: The Alkaline Earth Metals Unit 17: The Alkali Metals Unit 36: Sound and Hearing Unit 18: Metals and their Properties Unit 37: Natural Forces Unit 19: The Transitional Metals Unit 38: Cells, Tissue, Organs and Organs systems
2. Slide 2: Science Interactive LTD Copyright 2005 10 3 m 10 2m 10 1m 1m 10 -1 m 10 -2 m 10 -4 m 10 -6 m 10 -8 m 10 -10 m 10 -12 m radio waves (LW) (MW) (VHF) (UHF) microwaves Infra red light Ultra -Violet X - rays Gamma Unit 30  Light and the Electromagnetic Spectrum 
3. Slide 3: Unit 30: Light and the Electromagnetic Spectrum Science Interactive LTD Copyright 2005 Understand: Keywords: That visible light is just a small part of the much 1. Electromagnetic, Spectrum, Radio waves, larger electromagnetic spectrum. Ultrasound, Microwaves, Infra red, Visible, That the electromagnetic spectrum is a 2. Light, Ultraviolet, X rays, Gamma rays, collection of waves with similar properties. Radiation, Speed, Reflection, Refraction, That these waves have different uses based on 3. Wavelength, Rainbow, Eye, Lens, Retina, their individual properties. Cornea, Optic & Image. That the speed of light can be calculated using 4. Michelson’s experiment. That visible white light is a collection of the 5. seven colours of the spectrum. That visible light can either be reflected or 6. refracted. Some of the examples of devices that rely on 7. reflection or refraction of visible light. That visible light can be totally internally 8. reflected, for example in optic fibres. The similarities between the human eye and a 9. camera. 10. How the human eye forms an image. Click mouse to begin Science Interactive LTD PO BOX 50764 LONDON NW6 9AT web: www.science-interactive.co.uk email: sales@science-interactive.co.uk
4. Slide 4: Science Interactive LTD Copyright 2005 Waves and their properties one Sound or light waves can be reflected, refracted and diffracted. The wavelength is the distance between two successive compressions (crest or troughs) The f____________ measured in hertz (cycles per second) is the number of complete vibrations in each second. The amplitude is the average height of a crest or trough from the midpoint or the undisturbed position. The size of the amplitude determines the v_________ of the sound. The wavelength or frequency determines the pitch of the sound. Wavelength and amplitude: Word bank: frequency volume Waves Waves from a single point source Wavelength & amplitude Diagram Crest Amplitude Source midpoint Trough Wavelength Velocity of wave Speed: 330m/s From a single point source, waves like ripples on a pond spread out in Notes Wavelength (cm) all directions. The distance between two successive compressions is Amplitude (cm) known as the wavelength. The amplitude is the average height of a crest or a trough from the midpoint. What happens to the volume and pitch of a Frequency (Hz) sound, if you alter the amplitude and wavelength ?
5. Slide 5: Science Interactive LTD Copyright 2005 Waves and their properties two There are two types of w_______, longitudinal and transverse waves. Longitudinal: These waves travel from the source in waves of compression, parallel to the direction of the moving wave. Sound waves are longitudinal waves. Transverse: These waves travels from the source at right angles to the direction of the wave. Light waves are transverse waves. Types of waves: Word bank: waves frequency Waves Transverse...Light Longitudinal...Sound Diagram Direction of wave Direction of wave Transverse: The wave travels from the source at right angles to the direction Wavelength (cm) of the wave. Longitudinal: These waves travel from the source in waves of compression parallel to the direction of the moving wave. Remember: The Amplitude (cm) pitch of a sound is determined by the wave’s frequency and is measured in hertz. The volume level in decibels is determined by the wave’s amplitude. Frequency (Hz)
6. Slide 6: Science Interactive LTD Copyright 2005 Analogue or digital We now live in a digital age, for example digital r_____ and TV...but what does this all mean ? Analogue waves carry information from a transmitter in smooth varying waves, that can have a changing wavelength and amplitude. Analogue waves can be subject to interference and corruption. In digital systems, for example digital radio, the analogue carrier wave is converted to definite values usually on or off or 1’s and 0’s. Digital signals are less affected by interference from other sources. Digitally stored data like mp3 files are reconstructed into their original analogue sound waves during their play through a sound system. Analogue or digital: Word bank: radio Digital media Analogue Digital Diagram Digital code 011111011 01111101 0111111 011111 01011 01001 0111 0101 011 01 Direction of wave Direction of wave Radio, television and Recorded, transmitted and stored music, for example mp3 files are broadband now all rely stored as a series of numerical values (1’s and 0’s) rather than on digital systems to fluctuations in wavelength and amplitude of analogue sound. Over transfer all types of the last decade, digital medium (music radio, television and information, error free. photography) has replaced its older counterparts.
7. Slide 7: Science Interactive LTD Copyright 2005 The electromagnetic spectrum Visible light is only a very small fraction of a much larger spectrum containing many other waves with their own individual properties. These family of waves, unlike visible light cannot be seen with the human eye. Their properties change according to their w___________. These family of waves do share some properties, for example, they all travel at the same s_______ through a vacuum and are able to transfer energy. Give one use for each of the waves listed below ? The electromagnetic spectrum: Word bank: wavelength speed Wavelength (m) 103m 102m 101m 1m 10-1m 10-2m 10-4m 10-6m 10-8m 10-10m 10-12m radio waves (UHF) Wave (LW) (MW) (VHF) microwaves Infra red light Ultra-Violet X-rays Gamma Buildings Stonehenge Relative size Human Insect Pinhead Cell Molecule Atom Picture
8. Slide 8: Science Interactive LTD Copyright 2005 Sources and detecting electromagnetic waves The Sun gives out all the wave forms of the e.m spectrum however, only a small percentage including visible l_______ reaches the Earth’s surface. This is because our atmosphere stops many of the harmful waves reaching us. Visible light can be detected by the human e_____. Skin can also detect infra red waves as heat. In order to detect other waves forms like infra red radio waves, we need to use a device or detector. Sources and detection of electromagnetic waves: Word bank: light eye Wavelength (m) 103m 102m 101m 1m 10-1m 10-2m 10-4m 10-6m 10-8m 10-10m 10-12m Wave radio waves microwaves Infra red light Ultra-violet X-rays Gamma Wave Radio Microwaves Infra red Light Ultraviolet X rays Gamma Transmitters Ovens Sources Hot objects Sun Sun X ray tubes Radioactive substances Radar Sun Hot objects Mercury lamps Detectors
9. Slide 9: Science Interactive LTD Copyright 2005 Properties of all electromagnetic waves Electromagnetic waves consist of oscillating electric and magnetic fields, which all travel at the speed of light. The spectrum of electromagnetic waves ranges from very long wavelengths, for example r________ waves to very short wavelengths like g______ and x-rays. All these types of radiation are produced by excited atoms and their sub atomic particles (Neutron, Protons and Electrons) and during nuclear fission. Give two uses for gamma rays and radio waves ? Properties of all electromagnetic waves: Word bank: radio gamma Speed Energy transfer Reflection Refraction Diagram All electromagnetic All electromagnetic All electromagnetic All electromagnetic Notes waves travel at a speed waves are able to waves, like visible light waves like light can be of 300,000 kms-1 through transfer energy from can be reflected by bent, when they travel a vacuum. Nothing in one place to another. smooth, hard surfaces through transparent the known universe Infra red rays transfer, like a mirror. The angle materials like glass and travels faster than light for example heat of incidence is equal to water. This is called or other e.m waves. energy. the angle of reflection. refraction.
10. Slide 10: Science Interactive LTD Copyright 2005 The electromagnetic spectrum one Radio waves are a family of waves, with relatively long wavelengths. Medium and long wave radio are used to transmit signals over long d_________, because they are reflected around the curve of the Earth’s atmosphere. Microwaves have the shortest wavelength of radio waves and are used to h______ food in ovens as well as image planes. This is known as radar. Infra red, the next wave type, is given out by every warm object. Using infra red cameras, a thermograph can tell us the temperature of an object. The electromagnetic spectrum: Word bank: distances heat Wavelength 103m 102m 101m 1m 10-1m 10-2m 10-4m 10-6m (m) radio waves (LW) (MW) (VHF) (UHF) Diagram microwaves Infra red Radar Wave Radio waves Microwaves Infra red Diagram Notes Radio signals carry Radar uses microwaves, Microwave ovens and Infra red rays are given off sound information and to obtain information mobile phones use by all warm objects. You can travel many on the position of microwaves. In micro- cannot see these rays but kilometres through the planes in the sky. These waves, energy is your skin can sense them. Earth’s atmosphere waves are bounced transferred from the Above, a thermograph of a and ionosphere. back and collected by waves to the food. small infant. radar dish.
11. Slide 11: Science Interactive LTD Copyright 2005 The electromagnetic spectrum two Visible light is only a very small fraction of a much larger spectrum called the electromagnetic s_________ which contains many other wavelengths. Light is released from various sources including the Sun and hot objects like a b_____ filament. Visible light has wavelengths between 750 and 400 nanometres. The wavelength in nanometres, determines the colour of light, for example longer wavelengths (750nm) are red in colour and shorter wavelengths (400nm) are violet in colour. What wavelength in nanometres is infra red ? The electromagnetic spectrum: Word bank: spectrum bulb Wavelength (m) 10-6m 10-7m Diagram light Human eye Wave Visible light Separating light Communicating Diagram Notes The Sun, light bulbs The human eye has White light can be Pulses of light can carry and hot objects all emit evolved to make use of separated into its 7 information. Broadband visible light. They only a very small spectrum colours: This internet currently uses travel in a straight lines fraction of the e.m. can be done by a glass optic cables to carry through a vacuum at a spectrum. It can detect prism or rain drops large amounts of speed of 300,000 kms-1. all seven colours. (ROYGBIV) information.
12. Slide 12: Science Interactive LTD Copyright 2005 The electromagnetic spectrum three Waves with shorter wavelengths including, UV rays, X-rays and Gamma rays have a higher penetrating ability. X-rays, produced by an X-ray tube penetrate soft tissue. They are used to image broken b_______. Gamma-rays, with the shortest wavelength can penetrate even concrete and lead. Gamma rays carry high amounts of e________ and are very dangerous. They are used to sterilise food and medical instruments. The electromagnetic spectrum: Word bank: bones energy Wavelength (m) 10-8m 10-10m 10-12m Diagram Ultra-violet X-rays Gamma X-Rays Wave UV Light Gamma rays Diagram Notes UV rays produced by the Sun X-Rays can penetrate soft tissue Gamma rays penetrate thick can penetrate and damage skin but not hard bone. These rays concrete and lead. They are cells causing skin cancer. are used to image broken bones. used to sterilise foods, killing Pictured above is a sun bed Long term exposure can cause all bacteria present on the using UVB rays for a suntan. cancer. food’s surface.
13. Slide 13: Science Interactive LTD Copyright 2005 Visible light Our eyes are only sensitive to visible light. The light we see has a wavelength range of between 750 to 400 nanometres (1000 nanometres = 0.001 millimetre.) White light is a mixture of s_______ colours. White light can be split by a glass p______. This is because when light travels through glass, different colours all slow down, but by different amounts depending on their wavelength. Red light (longer wavelengths) is slowed the least and so is refracted through the smallest angle. Violet light (shorter wavelengths) is slowed down the most and so is refracted through the largest angle. Spectrum of white light: Word bank: seven prism Sun Rainbow Splitting light Visible wavelengths Orange Yellow Indigo Green Violet Blue Red 750nm 600nm 500nm 400nm Infra red ultra violet The Sun is the primary Nature’s way of White light from a single source The spectrum of colours and source of white light, splitting white light. can be split using a glass prism. their wavelengths. The human and all the colours of Each raindrop acts like Violet is deviated the most eye is sensitive to red, green the spectrum. It a mini-prism. Here red because it has the shortest and blue light only. Much like supplies the Earth with light is bent the least wavelength. Red light with the a television, your brain uses all the light and heat and violet light is bent longer wavelength is deviated these primary colours to form energy that we require. the most. the least. all other colours.
14. Slide 14: Science Interactive LTD Copyright 2005 Calculating the speed of light A scientist called Albert Michelson used an octagonal mirror to measure the speed of light. He shone a single ray of light onto the octagonal mirror, which was then reflected back to a mirror on a distant mountain 36 km away. A m_______ on that mountain reflected the light ray back along the same path to the same mirror on the octagon. In one experiment, the octagonal mirror rotated sufficiently fast, so that the light coming back from the mountain hit mirror B. Mirror B had moved into the same place as mirror A was when the light ray left it. Calculating the speed of light: Word bank: mirror Experiment Source B Mirror A Distance between source and mirror 36 km Calculation Revolution rate Time elapsed for Total distance travelled Speed of light Show your 1: How many (2) The octagonal (3) How long (in seconds) did (5) How far did the working degrees (o) would mirror rotated at the octagonal mirror take to light travel in metres out. the octagon turn 31250 r.p.m. How make one complete revolution ? (72 km) ? through so that many revolutions (4) How long did it take the mirror B is in in one second did (6) Use your answers octagon to turn so that mirror B exactly in the same the octagonal for a and b to calculate was in the same position as place as mirror A ? mirror make ? the speed of light (ms- mirror A ? )? 1
15. Slide 15: Science Interactive LTD Copyright 2005 Colour and light When white light (red orange yellow green blue indigo violet) illuminates a green object, it absorbs red, orange, yellow, blue, indigo & violet wavelengths, only leaving green light to be reflected into your eye. This is how the human e____ perceives colours. Colours used in paints and clothing work by absorbing most of the different colours in the spectrum, r___________ only the colour it appears. How does a glass prism separate the seven colours of the spectrum ? Coloured objects: Word bank: eye reflecting Mixing colour Colours Solving colours Diagram Red Blue Black Yellow Notes White light from the Materials like cloth Object colour Colours absorbed Colours reflected Sun or a filament bulb and plastic are dyed chemicals Red OYGBIV Red is a mixture of the using seven colours of the designed to reflect Blue ___________ ? _______ ? spectrum: red orange only certain colours Black ___________ ? _______ ? yellow green blue from the colour Yellow ___________ ? _______ ? indigo violet. spectrum.
16. Slide 16: Science Interactive LTD Copyright 2005 Addition of colour Adding the three primary colours: red, green and blue gives white light. In your eyes, on the surface of the retina, your cone cells are sensitive to these three primary colours. Adding two p_________ colours results in a secondary colour. There are three secondary colours: yellow, a purple like colour called magenta, and a greeny- blue colour called cyan. A television set uses all three primary colours (red, green & blue) to form a complete i________ showing a full range of colours. Adding colours: Word bank: primary image Mixing primary colours Television Diagram Notes The three primary colours red, green and blue A television uses only the primary colours, form white light in the centre as a result of red, green and blue to form a coloured mixing all three. The secondary colours image. The amount of primary light is (magenta, cyan & yellow) result when only two controlled by a chip to give the right image. primary colours are mixed.
17. Slide 17: Science Interactive LTD Copyright 2005 Reflection of light one Visible light travels in straight lines, unless it meets an object for example a mirror or a glass block. Reflection is the rebounding of l_____ from a smooth, shiny surface. Smooth surfaces such as clean glass, reflects light back to the observer in parallel rays. This is called regular reflection, where the angle of incidence is equal to the angle of reflection. Surfaces which are not smooth, for example the uneven surface of a road, diffuses light in all directions. This is called diffuse reflection. Understanding reflection: Word bank: light Regular reflection Diffuse reflection Reflection from a plane mirror Diagram The image looks Object as if it is here Actual path of light Imagined path of light Plane mirror Light is reflected by smooth, shiny The image appears to the observer as far away from the Notes materials like metals and glass. Rough plane mirror as the true object is in front. The above surfaces are poor reflectors of light. Light diagram shows how the reflected rays from a plane mirror can also dispersed in all directions by forms a virtual image. Notice that the angle of incidence is rough surfaces or even fog. equal to the angle of reflection (Example, both are 45o)
18. Slide 18: Science Interactive LTD Copyright 2005 Reflection of light two We can use different mirrors to reflect light in many ways. There are two kinds of mirrors; concave and c_________ mirrors. Concave mirrors converge parallel rays of light forming a focal point. For a near object, a concave mirror produces a magnified image. Convex mirrors s_________ or diverge parallel rays of light away from the imaginary focal point. The image in a convex mirror is always reduced in size giving a very wide field of view. Name three devices that use convex or concave mirrors ? Mirrors and their uses: Word bank: convex spread Convex mirror Concave mirror Torch Shop security Diagram A convex mirror is a A concave mirror is a A torch uses a concave Shop mirrors use a Notes diverging mirror. The converging mirror. The mirror to produce a convex mirror which image produced by a image produced by a beam of light from a produces a wide field of convex mirror, is concave mirror, is single point source or view. Why are these virtual, always larger virtual, always smaller bulb. What is the mirror types of mirrors used in and the right way up. and the upside down. made from ? shops.
19. Slide 19: Science Interactive LTD Copyright 2005 Reflection of light three We can use different mirrors to reflect light in many ways. There are two kinds of mirrors; concave and convex mirrors. Concave mirrors converge p________ rays of light forming a focal point. A concave mirror can be used to focus the Sun’s rays to collect light energy. They can also be used to collect sound radar, and television signals. Sky television require the installation of a satellite dish, which is c_________ in shape, attached to an outer wall. This dish will collect and focus signals from a satellite in a geostationary orbit. Describe how a solar cooker works using a concave mirror ? Mirrors and their uses: Word bank: parallel concave Convex mirror Concave mirror Diagram Convex mirror Concave mirror Object Object Image Image Both convex and concave mirrors alter the way we see an image of an object. This is because, Notes unlike plane mirrors their surface changes, therefore altering the way we see the image.
20. Slide 20: Science Interactive LTD Copyright 2005 Using mirrors and reflected light one The viewing periscope uses a simple arrangement of plane mirrors both placed at 45o to the viewing object. Periscopes are found in s___________ to view their targets, perhaps an aircraft carrier or frigate. You can also use a periscope to view a pop band over a crowd. Design with the use of mirrors a device that can check for bombs or other objects that might be attached to the underneath part of cars...show your design with a diagram...remember to use your ruler when drawing light rays ! Mirrors and the periscope: Word bank: submarines Inside a periscope Periscope Image Diagram Object Image Notes Rays from the object are reflected by plane The periscope allows you to observe what is mirrors both set at 45o in the periscope. The happening on the sea’s surface, when you are in a image is virtual, smaller but the right way up ! submarine. The target is a frigate ship.
21. Slide 21: Science Interactive LTD Copyright 2005 Using mirrors and reflected light two The reflecting telescope designed by Isaac Newton has a large concave mirror to collect reflected light from a d________ object like a planet in our solar system. The concave mirror also converges the light to a small plane mirror for the observers e_____. The eye lens acts like a magnifying glass to increase the size of the virtual image. Why should you never observe the sun using a pair of binoculars or a telescope...How can you safely observe the Sun during a solar eclipse ? Mirrors and the Newton telescope: Word bank: distant eye Newton’s telescope Telescope Image Diagram Notes Reflected light from a distant object like a An image of Saturn’s rings obtained using a planet enters the telescope. It is reflected Newton telescope. Telescopes like this one can be using a concave mirror and then enlarged bought relatively cheaply. Best used away from through an eye lens. major cities and light pollution.
22. Slide 22: Science Interactive LTD Copyright 2005 Refraction of light one Refraction is the bending of light waves when they pass from one medium (e.g. air) to another (e.g. glass.) If the s_______ of light is different in the two media, then light bends from its original path. The amount of bending depends on the material, the wavelength and the angle of entry. When light is slowed down, it will bend towards the normal, when light speeds up it bends a______ from the normal. This is the law of refraction. Refraction of light: Word bank: speed away Example one Example two Example three Example four Diagram Notes Example one: The spoon in this picture appears broken or interrupted. Example two: Light travelling through air, then water and glass is refracted because it is changing speed. Example three: The effect of refraction in this picture is to magnify the writing. Example four: A prism is able to separate white light into its separate colours, using refraction.
23. Slide 23: Science Interactive LTD Copyright 2005 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. Equation Substance Refractive index Speed of light (kms-1) Water 1.33 225,000 Speed of light in air Air 1.0 300,000 Refractive index = Speed of light in substance Diamond 2.4 120,000 Glass 1.5 200,000 Refraction of light through water Refraction through different materials Diagram Virtual image Glass Water Plastic Observer 38.2o 34.5o 40.5o Real position Notes If you are trying to hunt fish with a spear, Light rays travelling from air to glass slows down and are you have to allow for refraction. This is bent towards the normal. Light rays travelling from glass because of the effects of light changing to air speed up and are bent away from the normal. The speed when leaving water to air. Where normal is at right angles to the media interface. The would you aim the spear ? incoming and outgoing light rays are both parallel.
24. Slide 24: Science Interactive LTD Copyright 2005 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: Word bank: bend convex Convex lens one Convex lens two Convex lens three Diagram Notes The image produced using a A convex lens converges the The stronger the convex convex lens is virtual, smaller light rays. The distance lens, the larger the image. and upside down. The focal between the lens and the focal Look at the picture above, point is produced by the lens point is called the focal which eyesight condition is slowing down and refracting the length. This distance depends corrected by glasses with light. on the strength of the lens. convex lenses ?
25. Slide 25: Science Interactive LTD Copyright 2005 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: Word bank: plastic sharp Concave lens one Concave lens two Concave lens three Diagram Notes The image produced using a A concave lens diverges the The stronger the concave concave lens is virtual, larger light rays. The distance lens the smaller the image. and the right way up. The focal between the lens and the focal Look at the picture above, point is produced by the lens point is called the focal which eyesight condition is slowing down and refracting the length. This distance depends corrected by glasses with light. on the strength of the lens. concave lenses ?
26. Slide 26: Science Interactive LTD Copyright 2005 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: Word bank: reflected surgery Internal reflection Diamond Optic fibres Fountains Diagram Light rays are reflected Light appears to be Optic fibres are used to Even in water, light is Notes off the internal walls of trapped giving this carry mainly electronic trapped and seems to the optic fibre. The diamond its information across the flows within the water advantage here is that characteristic ‘fire’ and world wide web. Its is to give this effect seen it can change direction ‘brilliance.’ Flawless very fast and known as at night when the inside the cable. diamonds have the best broadband. fountain is lit.
27. Slide 27: Science Interactive LTD Copyright 2005 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: Word bank: copper Total internal reflection Optic fibres Endoscopes Diagram Notes When light strikes the boundary There are now millions of Doctors use endoscopes to between a medium with a very kilometres of optic fibres examine areas inside the high refractive index and another underground that are able to body. Why does using an with a very low refractive index, carry information from endoscope decrease recovery the light is totally reflected. This computer to computer via the time and reduce risk during is called total internal reflection. world wide web. surgery ?
28. Slide 28: Science Interactive LTD Copyright 2005 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: Word bank: colour retina Tissue Function (complete table) Cornea Protects the lens and begins to focus Light rays. Pupil Allows light through the eye. Iris Controls the amount of light entering the eye. Lens Focuses light image onto r________. Aqueous humour Helps keep shape of lens. Vitreous humour Helps keep shape of the eyeball. Retina Contains all rod and cone cells to detect light and c_______. Fovea Helps see objects in close detail. Optic nerve Optic nerve: carries information to the brain.
29. Slide 29: Science Interactive LTD Copyright 2005 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: Word bank: environment camera Picture Diagram Notes Eye 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. Camera The camera forms an image which is upside down, smaller than the real object and virtual. This image is captured using photographic film.
30. Slide 30: Science Interactive LTD Copyright 2005 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: Word bank: retina cornea lens electrical optic Diagram Lens Ciliary muscle Suspensory ligaments Lens is thin, because The ciliary body Suspensory ligaments are Distant the rays from distant relaxes when your pulled tight by the relaxed object objects need to be eye focuses a distant ciliary muscle. This pulls the bent less to form a object. The lens is lens into a thin shape so that sharp image on the therefore pulled into the lens can focus a distant surface of the eye’s a thin shape. object like a stop sign. retina. Lens is fat, because The ciliary body Suspensory ligaments are Near rays from near objects contracts when your allowed loose by the object need to be bent more eye focuses a near contracted ciliary muscles. to form a sharp image object. The lens is This allows the lens to form on the surface of the therefore allowed to a fat shape so that it can eye’s retina. form a fat shape. focus a near object like a book.
31. Slide 31: Science Interactive LTD Copyright 2005 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: Word bank: focussed strong 20/20 vision Normal vision Short sighted Long sighted Diagram Long sighted Short sighted Convex lens Concave lens Notes 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 !
32. Slide 32: Science Interactive LTD Copyright 2005 Extension questions and homework 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. Diagram Refraction Reflection Total internal Reflection Other examples One Two Three 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.
33. Slide 33: Science Interactive LTD Copyright 2005 4: Complete the table: Colours of light added Red + Green Red + Green Red + Blue Blue + Green Blue + Yellow together + Blue Appearance 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.