Chapter #12

Sound and Light

Chapter 12.1 NotesDecibels (dB) units used to measure sound intensity.

Infrasound any sound consisting of waves with frequencies lower than 20 Hz.

Ultrasound any sound consisting of waves with frequencies higher than 20 000 Hz.

• Resonance an effect in which the vibration of one object causes the vibration of another object at a natural frequency.

• Pitch the perceived highness or lowness of a sound, depending on the frequency of sound waves.

• Sonar (sound navigation and ranging) a system that uses reflected sound waves to determine the distance to, and location of, objects.

Sound waves are transmitted as vibrations into the ear and they bounce into the eardrum. Vibrations are then passed to the 3 bones and then transferred to the cochlea and to the auditory nerve.

Chapter 12.2 Notes

• Photon a particle of light.• Intensity the rate at which light or any

other form of energy flows through a given area of space.

• Radar a system that uses reflected radio waves to determine the distance to, and location of, objects.

• Radar stands for Radio Detection And Ranging

• Light can act as a wave or a particle.

• Electromagnetic spectrum- is the full range of light at different frequencies.

Chapter 12.3 Notes

• Light ray a model of light that represents light traveling through space in an imaginary straight line.

• Reflection is the bouncing off a light wave.

• Law of reflection states “The angle of incidence equals the angle of reflection”

Virtual image an image that forms at a point from which light rays appear to come but do not actually come from.

Real image an image of an object formed by many light rays coming together in a specific location.

• Colors are able to be seen because light is reflected back to your eyes.

Chapter 12.4 NotesRefraction- the bending of light waves when

they pass from one medium to another.

Refraction makes objects appear to be in different positions.

Refraction in the atmosphere creates mirages.

Mirage is a virtual image caused by refraction of light in the atmosphere. (looks like there is water on the road).

• Total internal reflection the complete reflection of light at the boundary between two transparent mediums when the angle of incident exceeds the critical angle.

So the 60* angle has total internal reflection

• Lens is a transparent object that refracts light rays, causing them to converge or diverge to create an image.

• Magnification a change in the size of an image compared with the size of an object.

• Prism is a transparent block with a triangular cross section.

• Dispersion is an effect in which white light separates into its component colors.

• Sunlight is dispersed and internally reflected by water droplets to form a rainbow.

Work Cited• “Sound wave”. May 8, 2008. http://www.privateline.com/TelephoneHistory/speech.jpg• “Decibel levels”. May 8, 2008. http://www.itap.purdue.edu/images/candy/hearingChart.jpg• “Cartoon”. May 8, 2008. http://imgs.xkcd.com/comics/resonance.png• “The Ear”. May 8, 2008.

http://www.infj.ulst.ac.uk/~pnic/HumanEar/Andy's%20Stuff/MScProject/workingcode_Local/humanear.jpg

• “Bus reflected image”. May 12, 2008. http://www.oxford-chiltern-bus-page.co.uk/upload121003/OX827-reflected-at-Water-Eaton.JPG

• “Leaf with color reflection”. May 12, 2008. http://www.shortcourses.com/images/b4ch4/greenobject.jpg

• “Glass of water”. May 13, 2008. http://webphysics.davidson.edu/faculty/dmb/EdibleOpticalMaterials/glass_of_water.jpg

• “Beaker with penny inside”. May 13, 2008. http://www.bbc.co.uk/schools/ks3bitesize/science/images/sci_dia_97.gif

• “Total internal reflection”. May 13, 2008. http://www.timbercon.com/Fiber-Optic-Glossary/images/Total-Internal-Reflection.gif

• “Lens”. May 13, 2008. http://www.abledata.com/product_images/images/02A0587.jpg• “Prism”. May 13, 2008. http://cache.eb.com/eb/image?id=7710&rendTypeId=4• “Rainbow on blue sky”. May 13, 2008.

http://www.eaas.co.uk/images/atmospheric_optics/rainbow.jpg• “rainbow over tree”. May 13, 2008. http://www.entheosweb.com/images/photoshop/rainbow_6.jpg