This is up until Wednesday 14th September

2. WAVES A wave carries consists of oscillations which move without carrying matter with them. The oscillations carry energy. The energy can be used to carry a signal.

3. Pulse A pulse is a single wave 'bump' or a “disturbance”. A pulse can easily be sent down a string or spring.

4. Amplitude Amplitude determines how much energy the waves have. More amplitude = brighter light, louder sound etc.

5. Wavelength = λ = lowercase (Greek) 'lambda'. What is the relationship between v, f and λ? http://www.science-class.net/Notes/Images_8th_Notes/Transverse-Wave.png Waves

6. Transverse Waves http://withfriendship.com/user/mithunss/transverse-wave.php

7. Longitudinal Waves Longitudinal waves are the opposite of transverse waves. The direction of propagation is the same as the direction of vibration in the medium. http://www.antonine-education.co.uk/Physics%20A%20level/Unit_2/Waves/Progressive_Waves/Trans_Long.htm

8. Train Analogy Speed = frequency * wavelength. V=fλ λ λ λ λ λ λ

9. Example Stella is swimming at a beach with waves constantly coming from the sea. She estimates that the distance between the wave crests is 6m, and two wave crests pass her every second. How fast are the waves travelling?

10. Example 2 Avinarsh shouts across the room at Paul. He shouts with a low frequency of 5000 Hertz, and the waves travel at a speed of 340 m/s. What is the wavelength of Avinarsh's voice?

12. State and explain the wave equation, including explaining why it works.

13. A. What is the time period of a wave if two waves pass every twenty seconds? B. What is the frequency of the wave from A? C. Hard: what is the relationship between time period and frequency (for any wave)? Write it like a math equation, using f for frequency and T for time period. It is ok if you can't do this question :)

14. The speed of sound in air is about three hundred and forty metres per second. 10. What is the frequency of a sound wave with a wavelength of 6.8 meters? 11. Humans can hear approximately twenty hertz to twenty kilohertz. Calculate the minimum and maximum wavelengths humans can hear. 12. The speed of light is 300 000 000 (3 * 10 8 ) meters per second. Calculate the wavelength of red light, given that it has a frequency of 500 000 000 000 000 (5 * 10 14 ) Hertz.

16. Hana is swimming in a wave pool. The wave generator creates two waves each second, and they travel at a speed of three metres per second. A. Will Hana notice the wave crests or troughs? B. How far apart are two crests or two troughs? Note for blog: This was not covered in class, but would be a good revision exercise.

17. Quantity Symbol Formula Unit Speed/ velocity V s = f* λ metres per second (m/s) f = v/ λ Hertz (Hz) λ (lambda)

19. Devise an experiment to calculate the speed of the waves in the water.

21. We can also draw them as a line through the middle of the wave, often called a ray .

22. What is the mathematical relationship between the ray and the wavefronts?

24. At a boundary a wave can reflect. http://science.jburroughs.org/mschober/waveslite/problem6solution.html

26. A change in speed causes a change in direction.

27. Depth of water changes the speed of waves. Image from Giancoli Physics, Sixth Edition. Please ask me if you would like to see the book it came from.

28. http://tap.iop.org/vibration/reflection/317/page_46713.html

30. The diffraction is generally only noticeable if the gap is not much larger than one wavelength. http://innovativescience.blogspot.com/2011/02/diffraction.html

32. All EM Waves A. Are transverse B. Can travel through a vacuum C. Travel at c, 3*10 8 m/s

34. What happens to the frequency as the wavelength increases?

35. What is the mathematical relationship between frequency and wavelength?

36. The Electromagnetic Spectrum http://www.kollewin.com/blog/electromagnetic-spectrum/

37. Electromagnetic Spectrum Wave Approximate Frequency Approximate Wavelength Uses Radio waves 10 3 m Microwaves 10 -2 m Infra Red Waves 10 -5 m Visible Light 5 *10 -7 m Ultraviolet Light 10 -8 m X Rays 10 -10 m Gamma Rays 10 -12 m seeing things; for cell phones and for heating things which contain water; transmitting signals; photographing bones which can't be seen with visible light; remote controls; identifying genuine or forged documents, and for purification of air and water; to sterilise food and seeds, and for cancer treatment

38. The words seeing things; for cell phones and for heating things which contain water; transmitting signals; photographing bones which can't be seen with visible light; remote controls; identifying genuine or forged documents, and for purification of air and water; to sterilise food and seeds, and for cancer treatment

40. A continuous variation is called an analogue signal, whereas digital signals are represented as numbers. Most early communications devices used analogue, while most modern devices use digital (exceptions?). http://news.bbc.co.uk/2/hi/technology/6142998.stm

42. Either the frequency or amplitude must be changed (modulation) to carry the signal. http://www.softwareforeducation.com/wikileki/index.php?title=FM

44. Absorption by the Atmosphere http://en.wikipedia.org/wiki/File:Atmospheric_electromagnetic_opacity.svg

46. Microwaves pass through the atmosphere, and can be reflected off satellites to pass signals around the Earth. http://yutok.blogspot.com/2007/09/broadband-internet-via-hf-radio.html http://www.indata.com/satellite_basics.html

48. FM signals are better quality, and are generally used in urban areas. http://scienceaid.co.uk/physics/waves/radio.html

50. Questions on page 95, 97 and 99.

52. They are thinner and lighter than electrical wire, and lose less signal over long distances. http://atlanticfo.co.uk/

54. Speed of sound

55. Noise and vibration

56. Pitch and volume (=frequency and amplitude)

57. Pages 100-107

58. 10A did the bookwork but not experiment Tuesday (fire drill)

59. 10B Wednesday

60. 10C Thursday (One slide completed already)

62. It can travel through liquids and all gases.

63. An oscilloscope can convert sound waves to visible transverse waves.

64. Humans can hear from around 20 Hz to 20 kHz, and the range decreases with range. A phone can typically carry waves ranging from 300Hz to 3.4kHz.

66. Questions on page 95, 97 and 99, 101.

67. Write answers in the most efficient way for your learning. I will only check completion; they are not 'assignments' and all material is covered in the notes,

69. Frequency = pitch

70. Amplitude = volume http://www.sciencelearn.org.nz/Contexts/The-Noisy-Reef/Sci-Media/Images/Graphs-of-sound-waves Pitch and volume image

72. Low note from a singer = 100Hz.

73. High note from singer = 1000Hz.

74. Whistle = 10 000 Hz. All images from wikimedia commons.

77. Sound level is measured in decibels (dB). http://impact.books.officelive.com/ProtectYourHearing.aspx Decibels scale image

79. It is difficult because sound comes from all around and bounces off walls etc. http://www.themotorreport.com.au/5928/toyota-to-fit-active-noise-cancelling-to-crown-hybrid Antinoise image

81. Try out the following simulations: http://www.kettering.edu/physics/drussell/Demos/waves/wavemotion.html

82. http://www.phy.hk/wiki/englishhtm/Lwave.htm

83. http://www.cbu.edu/~jvarrian/applets/waves1/lontra_g.htm

84. Sound can travel in many different media. Which properties of the medium will determine the speed of sound in it?

85. Answer: density (also elasticity – not grade 10 level).

86. Does sound travel faster in helium or air (mostly nitrogen)? Note: not covered with 10A yet

88. Formative – teacher view.

89. Instructions in handout.

90. Follow-up activities: Old IGCSE exam questions (handed out in class).

91. IGCSE June 2008 Question 2

94. Answer questions on page 103 and 107.

95. Note: this was only used for 10A on Tuesday 9/13 (fire drill); you will do the experiment and other slides next class.

98. However, most things which produce sound (especially musical instruments) produce other notes, called overtones, which make notes of the same frequency sound different.

99. If two notes are an octave apart, one has double the frequency of the other.

101. Compare your result to the official value. Write a comparison – more? Less? Reasonable? Why might they be different?

102. A number without a unit is meaningless.

104. Ripple Tank will be summative.

105. Speed of Sound and IGCSE exam will be formative.

106. We have now finished the sections on sound, waves and the EM spectrum.

112. Light can be drawn as rays, where the ray is perpendicular to the w___________.

113. Light (rays) must travel in s______ l_______.

114. The eye detects light (more later). Some things emit light (eg __________) while most things we see reflect light (eg _____________________) http://commons.wikimedia.org/wiki/File:Gluehbirne_2_db.jpg

115. Electromagnetic Spectrum Visible light has a wavelength of approximately 400 to 750nm (_________________) . Our eyes are probably sensitive to these frequencies because ____________________ _____________________. http://commons.wikimedia.org/wiki/File:Electromagnetic-Spectrum-Hebrew.png

117. Laser light is all the same frequency (c________) and all in phase, meaning that the troughs and crests are all in the same place. Lasers have many uses:

118. Fibre optics (data)

119. Medical Operations

120. Cds/DVDs http://electricly.com/wp-content/uploads/2010/05/white-mono-chromeatic-Laser-diodes.png http://commons.wikimedia.org/wiki/File:Laser_show_disco_(2).jpg

121. http://electricly.com/wp-content/uploads/2010/05/white-mono-chromeatic-Laser-diodes.png

122. Holograms A hologram is a 3D image made using lasers. They are often added to important documents and to make forgery more difficult. http://upload.wikimedia.org/wikipedia/commons/8/85/Rainbow_hologram.jpeg

124. Reflected rays follow three rules: 1. The angle of incidence equals the angle of reflection. 2. The incident ray, normal and the reflected ray all lie in the same plane. Angle of incidence Angle of reflection http://upload.wikimedia.org/wikipedia/commons/b/b2/Ray_optics_diagram_incidence_reflection_and_refraction.svg θ i = θ r

126. 1. the same size 2. the same distance from the mirror 3. laterally inverted (left and right swapped).

127. A great site below: http://www.kss.sd23.bc.ca/staff/jstracha/physics_11/course_material/unit8/U08L01/pages/ray7_plane_jpg.htm

129. The Dog at the Beach http://www.flickr.com/photos/velo4it/1746214612/ (no need to load this URL unless you like pictures of dogs and/or the beach)

130. How the Dog Runs http://commons.wikimedia.org/wiki/File:Dog_retrieving_stick.jpg http://commons.wikimedia.org/wiki/File:2009-11-19_(31)_Branch,_Ast.JPG http://commons.wikimedia.org/wiki/File:Brittany_Spaniel_Dog.jpg

131. How the Dog Runs http://commons.wikimedia.org/wiki/File:Dog_retrieving_stick.jpg http://commons.wikimedia.org/wiki/File:2009-11-19_(31)_Branch,_Ast.JPG http://commons.wikimedia.org/wiki/File:Brittany_Spaniel_Dog.jpg

133. As light enters a more dense medium, it slows down, and bends ____________ the normal.

134. As light enters a less dense medium, it speeds up, and bends ____________ from the normal. http://www.daviddarling.info/images/refraction.gif

136. Why Something Looks Bent in Water http://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Pencil_in_a_bowl_of_water.svg/1000px-Pencil_in_a_bowl_of_water.svg.png

138. This is why a prism can separate white light into its different colours.

139. This process is known as dispersion. http://upload.wikimedia.org/wikipedia/commons/0/06/Prism_rainbow_schema.png

140. Angles

141. The Semi-Circular Block The angle if incidence is always ________.

142. The Critical Angle is the angle for which the refracted ray has an angle of reflection of 90 °.

144. If the refracted light has an angle of refraction greater than the critical angle, the light is instead reflected. This is called total internal reflection.

146. While you are using the ray boxes, also observe and draw how light refracts through a rectangular perspex block. http://www.one-school.net/Malaysia/UniversityandCollege/SPM/revisioncard/physics/light/images/criticalangle.png

147. Fibre Optics http://en.wikipedia.org/wiki/File:Fiber_optic_illuminated.jpg

148. Why Do Diamonds Sparkle http://commons.wikimedia.org/wiki/File:CZ_brilliant.jpg

150. Convex Lenses A convex lens can produce a real image. A real image forms when light leaves an object and meets somewhere else. The object appears to be where its image is.

152. upright or inverted

153. real (light focusses there) or virtual (light looks like it focuses there).

154. Real Images A real image can be focussed onto a screen. The object appears to be where the image is. If it is bright and clear enough, a real image can trick the eye (and person) into thinking that something is really there. C F F Ray 1: Parallel to the principle axis and through the focus. Ray 2: Through the optical centre. Ray 3: Through the closest focus and then parallel to the principle axis. principle axis

157. Lens Calculations d o = distance from object to lens d i = distance from image to lens F = focal length C = centre of curvature = 2F

158. Convex Lens Summary object position Image position Real /virtual Enlarged / Diminished / same size Upright / Inverted Use (if any) Beyond C On C Between C and F On F Between F and the Lens

159. CAMERA Film/ CCD If the image were a very, very long way away, what would the distance from the lens to the film be?

161. Light always diverges (spreads out).

162. Parallel light rays spread out as if they had come from a point called a focus.

163. Images will always be _______, ______,and ________.

164. Concave lenses will not be examined in IGCSE exams. http://en.wikipedia.org/wiki/File:Lens1b.svg This site explains lenses very well: http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/imggo/ccv.gif

166. Concave lenses are also called diverging lenses.

167. Concave = “going into a cave”.

169. Parallel light rays converge at the __________. Objects nearby produce light rays which are not parallel. Light rays fro m an object of finite d o will meet at a distance d i . This distance can be found using a ray diagram or calculations. DON'T FORGET ARROWS!! sun

171. Answers