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### Transcript of Light and sound science 2 ESO Bilingual

• 1.2 ESO BilingualJulia McDonald January 24, 2011

2. Question 1: Light

• Where does light come from? How does it travel?

• Light can come from a natural source, like the sun, or from an artificial source, like a light bulb, flashlight, or candle.
• It travels in very small particles calledphotonsand moves in waves in astraight line .
• Light waves can move through air, water, glass or other mediums.

4. Question 2: Light

• Classify the following objects as transparent, translucent or opaque:
• Wood
• Tissue paper
• Aluminum foil
• Marble
• A page in a book
• Lenses in a pair of glasses

5. 2. Notes

• Transparent: All light can travel through
• Translucent: Some light is absorbed, most light passes through
• Opaque: Almost all light is absorbed. Light does NOT travel through.

6. Question 3: Light and Reflection

• Describe how the mountains are reflected in the water in the photograph of the lake.

• When a ray of light hits a surface, it bounces off and begins to travel in a different direction.
• The incident ray hits the surface, and the reflected ray bounces off the surface.

If the surface is shiny, the reflection is clearer. 8. Question 4: Light

• Describe the photograph of the flower in your book. Why does the stem look bent?

• Because the light is REFRACTED!
• Light is refracted when it passes from one medium to another medium with a different density.
• The lights BENDS at the boundary between the two.

10. Question 5: Light

• What kind of lens is used in a peephole in a door, converging or diverging?

• Peep-hole lenses are CONVERGING.
• Converging lenses : thicker at the center than at the edges. They concentrate rays of light. A magnifying glass is an example of a converging lens.
• Diverging lenses : thicker at the edges than at the center. They disperse rays of light. People who are short sighted have this in their glasses.

12. Question 6: Light

• What is the difference between ultraviolet light and infrared light? Can they be seen?

13. Question 6: Ultraviolet Light

• Ultraviolet isinvisibleto the human eye, but most people are aware of the effects of UV: A SUNBURN!
• The UV spectrum has many other effects, both beneficial and damaging, to human health.
• Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays.
• It is so named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet.
• UV light is found in sunlight and is emitted by electric arcs and specialized lights such as black lights.

14. UV bath in Russia 15. Question 6: Infrared Light

• Infrared (IR) light wavelengths are longer than that of visible light, but shorter than that of terahertz radiation microwaves.
• Infrared imaging is used for military and civilian purposes. Military applications include surveillance, night vision, tracking. Non-military uses include thermal (heat) analysis, temperature sensing, and weather forecasting.
• Infrared spectroscopy examines absorption and transmission of photons in the infrared energy range, based on their frequency and intensity.

16. IR Light 17. Question 7: Sound

• How does sound travel? Can it travel in a vacuum?

• Sound is a form of mechanical energy which is produced by the vibration of an object.
• Sound travels in waves through solids, liquids and gases. It always travels through a medium and cannot travel in a vacuum, like light can.
• The speed of sound depends on the medium. The denser the substance, the faster sound travels through it.

19. Question 8: Sound

• How would you define the three qualities of sound: Intensity, Pitch and Tone?

• Intensity: Sound can be loud or soft, depending on the amplitude (the maximum displacement of a periodic wave) of the sound wave. and is measured in decibels.
• Tone: Tone allows you to identify the source of a sound... instruments have different tones.
• Pitch: Sounds can be high or low depending on the frequency of their waves. Pitch identifies high and low notes of the same intensity.

21. Question 10: Sound

• What is the quality of sound that allows you to distinguish different voices?

• Tone!!!
• Tone allows you to identify the source of a sound.
• Instruments have different tones.

23. Question 10: Sound

• When two piano keys are played, what quality of sound is different?

• Pitch!!!
• Pitch: Sounds can be high or low depending on the frequency of their waves. Pitch identifies high and low notes of the same intensity.

25. Question 11: Light Pollution

• What is light pollution?

26. Question 11: Light Pollution

• Light pollution is excessive or obtrusive artificial light.
• Adverse effect of artificial light including sky glow, glare, light trespass, light clutter, decreased visibility at night, and energy waste.
• Light pollution is the alteration of light levels in the outdoor environment (from those present naturally) due to man-made sources of light.
• Light pollution is the introduction by humans, directly or indirectly, of artificial light into the environment.

27. Question 12: Sound Pollution

• What is sound pollution?

28. Question 12: Sound Pollution

• Noise pollution is excessive, displeasing human, animal or machine-created environmental noise that disrupts the activity or balance of human or animal life.
• The source of most outdoor noise worldwide is mainly construction and transportation systems, including motor vehicle noise, aircraft noise and rail noise.
• Indoor and outdoor noise pollution sources include car alarms, emergency service sirens, mechanical equipment, fireworks, compressed air horns, road equipment, barking dogs, appliances, lighting hum, audio entertainment systems, electric megaphones, and loud people.

29. Question 13: Sound/Noise Pollution

• Can you think of any Dos or Donts to reduce noise pollution?

30. Question 14

• Often, if you hear a recording of your own voice, you do not recognize it. Why do you think this is?

31. Question 15

• If you touch a bell when its ringing, the sound stops immediately. Why??
• What happens to the reverberations?

32. Question 16

• Does sound travel faster through a block of wood, or an inflated balloon?