Sources of visible light The sun Stars Light bulbs Fireflame 21413 Lightning Fireflies Laser pointers An object is seen only when an object emits or reflects light to the eye l uminous ID: 400743
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Slide1
Visible Light
Sources of visible light:The sunStarsLight bulbsFire/flame
2-14-13
Lightning
Fireflies
Laser pointersSlide2
An object is “seen” only when an object emits or reflects light to the eye.
luminous
Objects that generate their own light.Ex:
i
lluminated
Objects that are capable of reflecting light to our eyes.
Ex: Slide3
Speed of Light
Q: Does light travel faster through a solid, liquid or a gas? H: Light waves travel fastest through a _____ because_____. Slide4
Demonstration Slide5
Explanation
:Light travels the fastest through a gas (actually empty space) because there are less particles to move through and slow it down. Slide6
Reflection
Reflection – the bouncing of a light wave off a surface.
Law of Reflection - the angle of reflection is equal to the angle of incidence
2-13-14Slide7
Regular Reflection
Light waves reflect by the same angle. Diffuse Reflection
Light waves reflect at many different angles.Slide8
Laser Reflection Activity
Purpose: Compare reflection of visible light on different surfaces.
1. smooth 2. rough 3. shiny
4. dullSlide9
DO NOT SHINE LASER POINTERS NEAR ANYONE’S FACE – CAN CAUSE EYE DAMAGESlide10
Data Table:
Reflection
of Laser Pointer
Surface
(ex:
table, poster, curtains)
Surface Type(smooth, rough, dull, or shiny)
Reflection
Type
(regular or diffuse)
1.
2.
3.
4.
5.
6.
7.
8.
9. Slide11
Conclusion:
(Answer these questions in the RAP format. Restate, Answer, Prove. Use information from your data table for the prove part.)
Which types of surfaces had a regular reflection?Which types of surfaces had a diffused reflection?
Ex:
Smooth surfaces and shiny surfaces
have a regular reflection
. I could see the reflection from the laser pointer when I shined it on a soda can and the clock. Dull and rough surfaces
have a diffused reflection
.
There was no visible reflection off of a towel and a piece of paper when I shined the laser pointer at them. Slide12
Why does the pencil appear broken?
Refraction
2-14-14
Diagram:Slide13Slide14
Refraction
- the bending of light when light waves speed up or slow down as they pass through different substances Slide15
The more dense a substance is, the slower light travels through it.Slide16
Refraction Picture Contest
With a partner you will take pictures of light refracting. You will submit ONE for the contest. Your goal is to take the COOLEST most CREATIVE picture possible that demonstrates refraction!It MUST be a picture that YOU or your partner have taken!
We will vote on the best picture on Wednesday, February 19th in classEmail the picture to Mrs. Schneider by Tuesday night by 10:01 pm. Make sure both of your names on mentioned in the email. aschneider@lindberghschools.ws
For Full Credit – take an accurate picture of refraction and email it on time. Two extra credit points for the winners! Slide17Slide18
Behavior of Light
Three Ways Light Behaves:Reflects (Reflection)
Absorbs (Absorption) – the transfer of light energy to particles of matter
Ex: light becoming dim
Transmits (Transmission)
– the passing of light through matter
-includes refraction (light bending)
Ex: light passing through glass or water
2-25-13Slide19
How is Light behaving?
Ex 1. How does light behave when sun rays shine at a window?-Light transmits
through the window, reflects off of the window, and is absorbed into the window.
Ex 2.
How does light behave when you shine a flash light at a towel or a blanket?
-Light is
absorbed into the blanket, and reflects off the blanket at different angles (diffuse reflection)Slide20
Three Different Materials:
Transparent – a material that allows almost all the light to pass through and forms a clear image Ex:
Translucent – a material that allows most light to pass through and forms a blurry image Ex:
3.
Opaque
– a material that light cannot pass through
Ex: