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Light : What is Light? Light carries energy and travels as a wave.
Light travels at m/s or km/s (much faster than sound). Light waves travel in straight lines.
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Light : What materials will light travel through?
Hold different materials between the lamp and the screen. Use the results table and shading chart on the next slide to estimate the opacity of different materials.
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What materials let light through?
Shading chart. 100% 2.5 % 75 % 5 % 50 % 10 % 30 % 15 % 25 % 20 % 0% Opaque objects do not allow light to pass through them - transparent ones do. Translucent materials only let through part of the light.
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How does light travel? 1) Fill a clear glass trough or empty fish tank with smoke. 2) Shine rays of light through the tank and describe what you see. LIGHT WAVES TRAVEL IN STRAIGHT LINES.
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The light from the object enters our eye.
Seeing objects How do we see an object? The light from the object enters our eye. Do we see all objects in the same way? There are two ways we see objects….. We see some objects by reflected light. We see other objects because they are light sources.
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Light sources How do light rays from a light bulb and other light sources reach our eye? They travel in a straight line directly into our eye.
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Reflected light How do light rays from a book and other such (non-luminous) objects reach our eye? Light from the lamp or another light source strikes the book and some of the light is reflected into our eye.
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Reflection : Good or Poor?
Objects which reflect light well have smooth, shiny surfaces and are usually pale colours. They give clear images because they reflect the light regularly. Mirrors are excellent reflectors. Objects which do not reflect light well have rough, matt surfaces and are usually dark colours. They give no or diffuse images because they reflect the light irregularly.
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Reflection : Good or Poor?
Best Reflectors Red Roses Yellow Banana Tarmac Road White Paper Blue Car Polished Black Shoes Tangerine Green Leaf Al foil Tree Bark Worst Reflectors Arrange these items along the arrow:
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