Reflection and Reflection and RefractionRefraction

TEKS 5.6C

5.6 – The student knows that energy occurs in many forms and can be observed in cycles, patterns, and systems:

(C) Demonstrate that light travels in a straight line until it strikes an object or travels through one medium to another and demonstrate that light can be reflected such as the use of mirrors or other shiny surfaces and refracted such as the appearance of an object when observed through water

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Every second of every day our eyes detect and interpret rays of light – whether that light is coming from a natural source like the sun, or an artificial source like a lamp.

One of the properties of light is that it travels in a straight line, unless it is acted on by some external force or condition.

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However, sometimes our eyes can be fooled by the reflection and refraction of light. When interfered with, the path of light rays can be bounced or appear to be bent away from the original object making it seem larger or smaller than it really is.

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When light strikes a surface and is redirected back to its point of origin, this is reflectionreflection. We can see objects when they reflect light, and the reflected light enters our eyes.

Most objects reflect some of the light that hits them.

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

Light beams

Mirrors reflect images of objects because light rays bounce off an object, travel in a straight line to a mirror, bounce off the mirror, and then travel to the eye of the observer.

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Mirror

RefractionWhen the path of the light rays change directions and appear to bend we call it refractionrefraction.

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

amount of refraction depends on the angle the light enters the new substance and the difference in the densities of the two

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

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Refracting telescopes and regular camerasRefracting telescopes and regular cameras use lenseslenses to gather and focus light.

Reflecting telescopesReflecting telescopes gather and focus light with mirrorsmirrors. In a reflecting telescope, the observer sits inside the telescope, at the focal point of the reflected light.

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Decide whether each object below best represents reflection or refraction. Click on your answer to find out if you are correct.

reflection refraction

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You are correct – This picture illustrates reflection. Light bounces off of the object and does not pass through.

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You are correct. This picture illustrates refraction. As light passes through the object it is bent by the denser substance.

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Sorry, that is not correct

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One way solid objects are classified is by how much light is allowed to pass through that object.A transparenttransparent object lets allall of the light pass through.A translucenttranslucent object lets somesome light pass through.An opaqueopaque object lets nonenone of the light pass through.

transparent

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translucent opaque

You are about to see several objects. Your job is to decide if they are mostly transparent, translucent or opaque -

After you decide, click on the object to see if you are correct. 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.

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You are about to see several objects. Your job is to decide if they are mostly transparent, translucent or opaque -

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

This lampshade is translucent. Some of the light passes through, but not all of it.

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You are about to see several objects. Your job is to decide if they are mostly transparent, translucent or opaque -

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

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 man’s face behind the screen.

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You are about to see several objects. Your job is to decide if they are mostly transparent, translucent or opaque -

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

This sphere is transparent. You can clearly see the man inside. The man, of course, is opaque.

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You are about to see several objects. Your job is to decide if they are mostly transparent, translucent or opaque -

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

These pens are translucent. Enough light passes through to allow you to see some of the inside, but not enough to see everything clearly.

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You are about to see several objects. Your job is to decide if they are mostly transparent, translucent or opaque -

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

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The brick wall is opaque. You cannot see any part of the boy through the wall.

Now, try answering these questions:

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Unless acted upon, how does light travel?

A. Bent at a 500 angle.

B. In a straight line.

C. In a curved arch.

D. Light doesn’t 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 A – Although light is often bent at a 500 angle, that only happens when something acts upon it to make it change its path.

Answer C – Light does not usually travel in an arch.

Answer D – Light does have a preferred path – a straight line.

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All the following are examples of light being refracted EXCEPT —

A

B

C

D

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Answer choice D is correct. The mirror is using reflection to bounce light off of its surface.

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These answers are not correct because:

Answer A – Look at the bent light rays. A rainbow is the result of light being refracted.

Answer B – Look 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 object and be refracted, the object must be transparent (see-through) or translucent (semi-transparent).

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These answers are not correct because:

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

Answer B – A black surface would not necessarily allow light to pass through it.

Answer D – An opaque surface would not allow light to pass through it.

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In this picture, the straw appears 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 light is being refracted as it passes through the air into the liquid.

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These answers are not correct because:

A. An opaque substance – if the liquid were opaque, we would not be able to see the straw.

B. A magic trick – it is not a trick that the light is being bent, or refracted, as it moved through the liquid

C. Light being reflected – although some light may be reflected by the glass, that is not the reason 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 is reflecting the image of nearby buildings.

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These answers are not correct because:

A – Prism –light is being refracted as it passes through the prism

B - Rose Quartz – the surface of this rock is too 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 bent as it passes through the air and water droplets.

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

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

The End

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...