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Do Now Reflection Question

Do Now Reflection Question. Do Now Reflection Question. Refraction. Today’s lesson. Refraction of light Refraction of light by a prism is called dispersion Please remember to remain in you seats unless given permission Mirror Island Homework due in. The mug trick!. Beam of light.

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Do Now Reflection Question

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  1. Do Now Reflection Question Do Now Reflection Question

  2. Refraction

  3. Today’s lesson • Refraction of light • Refraction of light by a prism is called dispersion • Please remember to remain in you seats unless given permission • Mirror Island Homework due in

  4. The mug trick!

  5. Beam of light Beam of light Glass block Glass block Refraction of light

  6. WHY?

  7. A model for refraction

  8. Refraction in a glass block

  9. Refraction Beam of light Light going from air to glass bends towards the normal Glass block Light going from glass to air bends away from the normal

  10. Can you carefully add these notes to your diagram? Refraction Ray of light A light ray entering along the normal continues in a straight line. Glass block

  11. Please stick into your book; use a double page and then fill in.

  12. Light waves Light slows down as it goes from air to glass/water its speed changes from 3 x 108 m/s to 2 x 108 m/s or from 300 000 km/s to 200 000 km/s

  13. Water waves Water waves travel slower in shallow water

  14. Wavelength and speed effects

  15. Refraction – a few notes The wavelength changes, the speed changes, but the frequency stays the same. when a waves direction is changed it is deviated (deviation) Ripple Tank Simulation

  16. Refraction experiment Typical results air to glass: No deviation occurs when the angle of incidence is zero. Increasing the angle of incidence increases the deviation.

  17. Refraction experiment Air to Perspex Typical results air to Perspex :

  18. A B D E C F Complete the paths of the RED light rays:

  19. Let’s try some drawing!

  20. normals observer AIR WATER image object at the bottom of a pool Why a pool appears shallow

  21. white light prism spectrum Refraction by a prism – copy please • A prism splits the colours of white light into the spectrum. • This is called dispersion. • Violet light deviates the most shortest wavelength, • redthe least longest wavelength.

  22. Choose appropriate words to fill in the gaps below: Refraction occurs when a wave changes ______ as it crosses the boundary between two regions. The _________ of the wave also usually changes. Light rays deviate ________ the normal when they pass from less dense air to more dense _________. The greater the angle of incidence the greater is the _________. Different ______ of light deviate by different amounts. Violet deviates the _____. A prism can be used to split the colours of white light into a spectrum. This is called _________. speed direction towards perspex deviation colours most dispersion WORD SELECTION: towards deviation most dispersion direction perspex speed colours

  23. Refraction When a wave changes speed (normally when entering another medium) it may refract (change direction) Ripple Tank Simulation

  24. Snell’s law There is a relationship between the speed of the wave in the two media and the angles of incidence and refraction Ray i r

  25. Snell’s law speed in substance 1 = sin(i) speed in substance 2 sin(r) i r

  26. Snell’s law In the case of light only, this quantity is called the refractive index (η) η = sin(i) sin(r) i r

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