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Do now!

Do now!. Can you write the title “ P7 Waves ” in your books please? (Underlined with a ruler of course). P7 Waves. This lesson. What is a wave? Longitudinal and transverse waves Amplitude, wavelength, frequency and period of a wave The relationship between frequency and period

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Do now!

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  1. Do now! Can you write the title “P7 Waves” in your books please? (Underlined with a ruler of course)

  2. P7 Waves

  3. This lesson • What is a wave? • Longitudinal and transverse waves • Amplitude, wavelength, frequency and period of a wave • The relationship between frequency and period • The wave equation

  4. What is a wave? YouTube - Water bubble in Space (zero gravity) http://www.youtube.com/watch?v=xUnadiyPTks

  5. Waves Waves can transfer energy and information without a net motion of the medium through which they travel. They involve vibrations (oscillations) of some sort.

  6. Waves Waves can transfer energy and information without a net motion of the medium through which they travel. They involve vibrations (oscillations) of some sort. Can you do something very boring and traditional……… Can you copy this please?

  7. Rays Rays highlight the direction of energy transfer.

  8. Transverse waves The oscillations are perpendicular to the direction of energy transfer. peak Direction of energy transfer oscillation trough

  9. Transverse waves • Water ripples • Light • On a rope/slinky • Earthquake

  10. Longitudinal waves The oscillations are parallel to the direction of energy transfer. Direction of energy transfer oscillation

  11. Longitudianl waves compression rarefraction

  12. Longitudinal waves • Sound • Slinky • Earthquake

  13. Wave measurements

  14. Amplitude - A The maximum displacement from the mean position. amplitude

  15. Period - T The time taken (in seconds) for one complete oscillation. It is also the time taken for a complete wave to pass a given point. One complete wave

  16. Frequency - f The number of oscillations in one second. Measured in Hertz. 50 Hz = 50 vibrations/waves/oscillations in one second.

  17. Period and frequency Period and frequency are reciprocals of each other f = 1/T T = 1/f

  18. Wavelength - λ The length of one complete wave. wavelength

  19. Wave speed - v The speed at which the wave fronts pass a stationary observer. 330 m.s-1 YouTube - Bill Nye the Science Guy - 51: Waves 1/3

  20. The Wave Equation v =fλ v = speed (m/s) λ = wavelength (m) f = frequency (Hz) v f λ x

  21. Some example wave equation questions • A water wave has a frequency of 2Hz and a wavelength of 0.3m. How fast is it moving? • A water wave travels through a pond with a speed of 1m/s and a frequency of 5Hz. What is the wavelength of the waves? • The speed of sound is 330m/s (in air). When Dave hears this sound his ear vibrates 660 times a second. What was the wavelength of the sound? • Purple light has a wavelength of around 6x10-7m and a frequency of 5x1014Hz. What is the speed of purple light? 0.6m/s 0.2m 0.5m 3x108m/s

  22. Wave equation questions v λ f x

  23. Let’s try some questions! Page 125 (all the questions) and page 136 questions 1 and 4.

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