Light Sources And Traveling Light Sheet (Page 2 of 2) in pdf

Name:_________________________________________________

Div:_____

Date:___________________________________

Check your understanding 10.1

Traveling Light and Shadows:

1. Which of the following are luminous?

Shadows: area where light has been blocked by a solid object (eg, shade of a

a. A campfire

building or tree on a hot day)

b. The moon

c. A hot toaster filament

Umbra: portion of shadow that no light reaches

2. Make a flow chart to illustrate the process that each luminous object uses to

Penumbra: the lighter part of the shadow where no light reaches

emit light and the type of energy that is transformed into light energy.

In an eclipse, the light source is larger than the object in front of it; therefore,

a. The light in your home

b. A lit match

there will be both types of shadows. This would also happen with two light

c. Glow sticks

sources

d. Glow – in the dark paints and fabrics

3. What is the difference between a phosophorescent light source and a

fluorescent light source?

4. Describe how a flashlight can be luminous. Describe how it can also be non-

lumiunoius.

5. While cycling, your body’s efficiency is about 20 %. This means that your

body uses about 20 % of its available energy for cycling. The remaining 80 %

becomes heat. Incandescent bulbs have an efficiency of about 5 %,

fluorescent bulbs about 20 %.

a. Why does a bright incandescent bulb get much hotter than a bright

fluorescent tube?

6. What kind of light source would be safest to use in buildings or bines that

might be filled with explosive gas?

When the light source is smaller than the object, only an umbra is formed.

Check your understanding 10.3

1. Classify the following materials as transparent, translucent, or opaque:

Milk, apple juice, wax paper, aluminum foil, plastic wrap, mirror, helium, ice

cube, smoky air, writing paper, newspaper, cardboard, clear plexiglass,

coloured plexiglass, silk, rubber, copper plate

Transparent

Translucent

Opaque

Teacher notes:

2. Explain how climate is an important factor in deciding what type of building

On Board:- classifying objects

materials to use when constructing a house.

3. Why does fall and winter clothing usually come in darker colours, while

spring and summer clothing usually comes in lighter colours?

Light Sources And Traveling Light Sheet Page 2

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