2 ESO Bilingual Julia McDonald

January 24, 2011

Question 1: LightWhere does light come from? How does it

travel?

1. AnswerLight 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 called photons and moves in waves in a straight line.

Light waves can move through air, water, glass or other mediums.

Question 2: LightClassify the following objects as transparent,

translucent or opaque: WoodTissue paperAluminum foilMarbleA page in a bookLenses in a pair of glasses

2. NotesTransparent: 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.

Question 3: Light and ReflectionDescribe how the mountains are reflected in

the water in the photograph of the lake.

Question 3: AnswerWhen 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.

Question 4: LightDescribe the photograph of the flower in your

book. Why does the stem look bent?

Question 4: AnswerBecause 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.

Question 5: LightWhat kind of lens is used in a peephole in a

door, converging or diverging?

Question 5: AnswerPeep-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.

Question 6: LightWhat is the difference between ultraviolet

light and infrared light? Can they be seen?

Question 6: Ultraviolet LightUltraviolet is invisible to 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.

UV bath in Russia

Question 6: Infrared LightInfrared (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.

IR Light

Question 7: SoundHow does sound travel? Can it travel in a

vacuum?

Question 7: AnswerSound 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.

Question 8: SoundHow would you define the three qualities of

sound: Intensity, Pitch and Tone?

Question 8: AnswerIntensity: 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.

Question 10: SoundWhat is the quality of sound that allows you

to distinguish different voices?

Question 9: AnswerTone!!!

Tone allows you to identify the source of a sound.

Instruments have different tones.

Question 10: SoundWhen two piano keys are played, what quality

of sound is different?

Question 10: AnswerPitch!!!

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

Question 11: Light PollutionWhat is light pollution?

Question 11: Light PollutionLight 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.

Question 12: Sound PollutionWhat is sound pollution?

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.

Question 13: Sound/Noise PollutionCan you think of any “Do’s” or “Don’ts” to

reduce noise pollution?

Question 14Often, if you hear a recording of your own

voice, you do not recognize it. Why do you think this is?

Question 15If you touch a bell when it’s ringing, the

sound stops immediately. Why??

What happens to the reverberations?

Question 16Does sound travel faster through a block of

wood, or an inflated balloon?

Question 16: AnswerThe denser the medium, the faster sound

travels through it!

Block of wood