light power point 2013-2014

8/13/2019 Light Power Point 2013-2014

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Reflection andRefraction

TEKS 5.8B


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Day 1Vocabulary I Need to Know

Surface- The surface of the table is red.

Reflect- I can see my reflection in a mirror.

Refract- Refraction in the bending of light.

Absorb- Absorption happens when light that hits an object istaken in by the object. Black or dark objects absorb almost allthe light that hits them. White objects absorb almost no light.


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Every second of every day our eyes detect and

interpret rays of lightwhether that light is

coming from a natural source like the sun, or anartificial source like a lamp.

One of the properties of light is that it travels ina straight line, unless it is acted on by someexternal force or condition.

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However, sometimes our eyes can be fooled by

the reflection and refraction of light. Wheninterfered with, the path of light rays can bebounced or appear to be bent away from the

original object making it seem larger or smallerthan it really is.

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When light strikes a surface and is redirected back

to its point of origin, this is reflection. We can seeobjects when they reflect light, and the reflectedlight enters our eyes.

Most objects reflect some of the light that hitsthem.

Smooth, shiny surfaces that absorb very little light,will reflect light at almost the same angle that the

light hits it.

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Reflection


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Light beams

Mirrors reflect images of objects because lightrays bounce off an object, travel in a straight

line to a mirror, bounce off the mirror, and thentravel to the eye of the observer.

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Mirror

Complete the first activity located on your table with a partner.


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RefractionWhen the path of the light rays change directions and appear to

bend we call it refraction.

occurs when light passes from one substance to another of adifferent density(for example, from air to water)

amount of refraction depends on the angle the light entersthe new substance and the difference in the densities of thetwo

the greater the angle, the more the light ray will be bent

Activity 2: Place a pencil in the glass of water. How did the pencilchange? In your science journal illustrate and explain how the pencilchanged.

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Examples of Refraction

Prism Rainbow

Magnifying glass


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Refracting telescopesand regular camerasuse lensesto gather

and focus light.

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Decide whether each object below bestrepresentsreflection or refraction. Click on your answer to find outif you are correct.

reflection refraction

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http://www.thebeijingcenter.org/expeditions/excursions/minoritiestrip/3%20pagoda%20reflection.jpghttp://www.windycityart.com/california/Reflection.jpghttp://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/optpic/brokpen.jpg


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You are correct

This picture illustratesreflection. Light bounces off of the objectand does not pass through.

Back to pictures


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You are correct. This picture illustratesrefraction. As light passes through the objectit is bent by the denser substance.

Back to pictures


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Sorry, that is not correct

Back to pictures


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Day 2

One way solid objects are classified is by how much light is allowed topass through that object.

A transparentobject lets allof the light pass through.

A translucentobject lets somelight pass through.

An opaqueobject lets noneof the light pass through.

transparent

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translucent opaque

Complete the activity located at your table with your shoulder partner.


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You are about to see several objects. Your job is todecide if they are mostly transparent, translucent oropaque -

After you decide, click on the object to see if you arecorrect. Some pictures have two options.

This window is transparent.

You can clearly see the

image on the other side

because all of the light is

passing through.

This lampshade is

translucent. Some of the

light passes through, but not

all of it.

The computer is opaque. No

light is passing through, so you

cannot see anything behind it.

However, the screen is

transparent. That is why you

can clearly see the mans facebehind the screen.

This sphere istransparent. You can

clearly see the man

inside. The man, of

course, is opaque.

These pens aretranslucent. Enough light

passes through to allow you

to see some of the inside,

but not enough to seeeverything clearly.

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The brick wall isopaque. You

cannot see any

part of the boy

through the wall.

(NOTE: The next picture will come in automatically do not click again to

advance. Click only to check your answer.)


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Now, try answering thesequestions:

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Unless acted upon, how does light travel?

A. Bent at a 500angle.

B. In a straight line.

C. In a curved arch.

D. Light doesnt have a preferred path.

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Answer B is correct:

Light travels in a straight line.

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These answers are not correct because

Answer AAlthough light is often bent at a 500

angle, that only happens when something acts uponit to make it change its path.

Answer CLight does not usually travel in an arch.

Answer D Light does have a preferred path astraight line.

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All the following are examples of light being

refractedEXCEPT

A

B

C

D

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Answer choice D is correct. The mirror is

using reflection to bounce light off of itssurface.

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These answers are not correct because:

Answer ALook at the bent light rays. A

rainbow is the result of light beingrefracted.

Answer BLook at the bent light rays. A

prism bends light.

Answer C - The straw looks bent in this

picture. It is an example of refraction,not reflection.

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Which answer below names two conditions in

which refraction can occur?

A.Opaque and transparent

B.Transparent and black

C.Translucent and transparent

D.Translucent and opaque

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Answer choice C is Correct:

In order for light to pass through an objectand be refracted, the object must betransparent (see-through) or translucent

(semi-transparent).

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Answer A - An opaque object would not allow lightto pass through it.

Answer B A black surface would not necessarilyallow light to pass through it.

Answer D An opaque surface would not allow lightto pass through it.

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In this picture, the strawappears to be bent. This is

because

A.milk is an opaque substance.

B.light is being refracted.

C.it is a magic trick.

D.light is being reflected.

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Answer B is correct.

The straw appears to be bent because lightis being refracted as it passes through theair into the liquid.

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A. An opaque substanceif the liquid wereopaque, we would not be able to see the

straw.

B. A magic trick

it is not a trick that the lightis being bent, or refracted, as it movedthrough the liquid

C. Light being reflected although some lightmay be reflected by the glass, that is not thereason why the straw appears to be bent.

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Which of these objects best illustrates reflection?

A. Prism B. Rose Quartz

C. Window D. Paper

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Answer C is correct.

The smooth surface of the window isreflecting the image of nearby buildings.

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A Prism light is being refracted as it passesthrough the prism

B - Rose Quartz

the surface of this rock istoo rough to reflect light

D -Paper since paper is opaque, light would not

bounce off or be refracted.

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Look at the objects below. Which one uses

refraction?

A B

C D

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Answer Choice C is CORRECT.

A rainbow uses refraction. The light is bentas it passes through the air and waterdroplets.

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Answer choice A, B, and D are not correct.

Mirrors use reflection of light in order tosee an object, not refraction.

The

End


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Resources for images:

Transparent screen:

www.computeramerica.com/.../2005/2005-04-04.htmTransparent watch:

www.swatchforum.com/curiosities.html

Virtusphere:

www.virtusphere.net/product.htm

Opaque pitchers:

www.guild.com/artitem/30336.html

Transclucent penwww.promotional-pens.us/promotional-pens/basi...
http://www.computeramerica.com/.../2005/2005-04-04.htmhttp://www.swatchforum.com/curiosities.htmlhttp://www.virtusphere.net/product.htmhttp://www.guild.com/artitem/30336.htmlhttp://www.promotional-pens.us/promotional-pens/basic-translucent-writer-promotional-pens.htmhttp://www.promotional-pens.us/promotional-pens/basic-translucent-writer-promotional-pens.htmhttp://www.promotional-pens.us/promotional-pens/basic-translucent-writer-promotional-pens.htmhttp://www.promotional-pens.us/promotional-pens/basic-translucent-writer-promotional-pens.htmhttp://www.promotional-pens.us/promotional-pens/basic-translucent-writer-promotional-pens.htmhttp://www.promotional-pens.us/promotional-pens/basic-translucent-writer-promotional-pens.htmhttp://www.guild.com/artitem/30336.htmlhttp://www.virtusphere.net/product.htmhttp://www.swatchforum.com/curiosities.htmlhttp://www.computeramerica.com/.../2005/2005-04-04.htmhttp://www.computeramerica.com/.../2005/2005-04-04.htmhttp://www.computeramerica.com/.../2005/2005-04-04.htmhttp://www.computeramerica.com/.../2005/2005-04-04.htmhttp://www.computeramerica.com/.../2005/2005-04-04.htm

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