Grade 10 Light
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Grade 10 Light

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A set of slides created to teach Grade 10 Light to learners at Bishops Diocesan College in Cape Town.

A set of slides created to teach Grade 10 Light to learners at Bishops Diocesan College in Cape Town.

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  • 1. Light K Warne
  • 2. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Light Rays  Give evidence to show that light travels in straight lines • Draw ray diagrams to represent the way in which light travels.
  • 3. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Reflection of Light • Light is reflected (bounced) off surfaces.
  • 4. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Vision • Objects are seen when light reflects off them into our eyes.
  • 5. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Every day Refraction Refraction is seen in a number of everyday circumstances. • Water mirage on roads. • Distortion of images viewed through a glass prism. • Distortion of objects viewed in water.
  • 6. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Passage of light through a glass block A B AB is the incident ray. The emerging ray is parallel to the incident ray if the block is a rectangle. Indicate incident rays Indicate incident angles and refracted angles on your diagram. i r Angle of incidence Angle of refraction Refracted ray Emergent ray
  • 7. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Passage of light through a glass block On entering the glass (more optically dense) block the light is refracted TOWARDS the normal. On exiting the glass (more optically dense) block the light is refracted AWAY from the normal. A B AB is the incident ray. “i” is the incident angle i rThe light ray is refracted (bent) because : • it enters a medium of different optical density • At an angle (not 90o) BC is the REFRACTED ray. “r” is the angle of refraction. C D CD is the EMERGENT ray.
  • 8. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Refraction of waves • Waves …………… on entering a ……. ………. medium. • If the wave strikes this medium at …. ……….. it then changes …………. Normal line 90° to the surface The wave bends …………………………….. on entering a more dense medium at an angle. The waves bend …………………………….. when exiting a more dense medium.
  • 9. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Passage of light through a glass block On entering the glass (more optically dense) block the light is refracted TOWARDS the normal. On exiting the glass (more optically dense) block the light is refracted AWAY from the normal. A B AB is the incident ray. “i” is the incident angle i rThe light ray is refracted (bent) because : • it enters a medium of different optical density • At an angle (not 90o) BC is the REFRACTED ray. “r” is the angle of refraction. C D CD is the EMERGENT ray.
  • 10. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net “Mirage” on Road A “mirage” is simply an image of the sky that is formed by the refraction of light through air of varying densities due to temperature gradients. Sky Hot air cold air Light appears to come from road
  • 11. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Real and apparent depth Objects viewed in water……………… …………………… …………………… …………………… …In reality the object is not seen at all - only the image! Draw in the light rays - to show the formation of the image. Label the object, image, real depth and apparent depth.
  • 12. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Archer Fish • HW: Draw a ray diagram to show the refraction effects that must be taken into account by an archer fish if it is to “shoot” down an insect outside the water effectively. • THE FISH MUST AIM LOWER THAN • THE OBJECTAPPEARS! AIM
  • 13. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Real and apparent depth – HW 2 • Draw the position of the image. • Show by means of light rays why the object appears shallower than it is.
  • 14. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Total internal reflection
  • 15. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Optical Fibres • The light in a fiber-optic cable travels through the core (hallway) by constantly bouncing from the cladding (mirror-lined walls), a principle called total internal reflection. Because the cladding does not absorb any light from the core, the light wave can travel great distances. • However, some of the light signal degrades within the fiber, mostly due to impurities in the glass.
  • 16. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Triangular Prisim i r dN i=angle of incidence r=angle of refraction d=angle of deviation
  • 17. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Converging Lenses Parallel light rays Parallel to principle axis Parallel light rays Refracted towards a centre point – we say they converge to a point.
  • 18. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Diverging Lenses
  • 19. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Ray Diagrams – Centre line Principle axis In a thin lens the displacement is negligible. The rays are drawn as if refracting from the center line. . F
  • 20. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Ray Diagrams - Optical Centre Principle axis Light rays passing along the ……………….. are ……… …………………… as they strike both surfaces at 90° Any ray passing through the ………….. …………. can be thought of as passing …………… ……………. In a thin lens the displacement is negligible.
  • 21. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Ray Diagrams -Focal Point ……………………. … .... F ……... ……….. • Any ray striking the lens ………… to the principle axis is refracted through the …………….. point. These values are the ………… for either side of a ………...………… lens. Parallel to ………………… ……….. ……………. ……. •••
  • 22. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Diverging Lenses F F -……. ………. ……. …………..• In a diverging lens the rays …………………. to have originated at the ……………… point.
  • 23. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Ray Diagrams • Three rays can be used to find the image of any lense.
  • 24. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Light PracticalPart I Measure the angle of incidence when the angle of refraction is 90° Part II • Optical bench – measure: the distance from the object to the lens (Do ), height of the object (Ho) and the distance from the image to the lens (DI) and the height of the image (Ho ). Write up method – and give a diagram! RESULTS Do (Ho) Di Hi (relative to Ho) . 1 >2F between 2F and F diminished (smaller) 2 At 2F 3 2F > x > F 4 At F 5 < F
  • 25. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Light Practical Object Image Do Di Ho Hi Do greater than 2F Do equal to 2F Do less than 2F F= 50cm Ray diagrams p 39
  • 26. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Light Practical Object Image Do Di Ho Object further than 2F Image: • Between F & 2F • Inverted • Real • Diminished F • F • 2F • 2F • HI Magnification = = = 0.44Hi Ho 1.9 4.3 Magnification = = = 0.5 Di Do 3.8 7.6 Do greater than 2F, Do equal to 2F, Do between 2F & F, Do equal to F, Do less than F
  • 27. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Compound Microscope F•2F F F 2F
  • 28. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Eye - Defects This is commonly called short sighted. Object Far away Distant objects the lens is not stretched enough. (Too fat) Rays are focused in front of retina are blurred. Object close up are focused clearly. A diverging lens would cause distant rays to focus on the retina and normal sight is restored. Short Sighted Corrective glasses
  • 29. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net From World Book © 2002 World Book, Inc., 233 N. Michigan Avenue, Suite 2000, Chicago, IL 60601. All rights reserved. World Book illustrations by Charles Wellek From World Book © 2002 World Book, Inc., 233 N. Michigan Avenue, Suite 2000, Chicago, IL 60601. All rights reserved. Nikon, Inc. Eye vs Camera ENLARGE
  • 30. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Hi - This is a SAMPLE presentation only. My FULL presentations, which contain loads more slides (with all the gaps filled in) as well as other resources, are freely available on my resource sharing website: www.warnescience.net (paste into your browser if link above does not work) Have a look and enjoy! Keith Warne