light and color 4 th grade science. core content unifying concepts sc-04-4.6.4 students will:...
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Core Content
Unifying Concepts• SC-04-4.6.4• Students will: • analyze models/representations of light in order to
generalize about the behavior of light. • represent the path of light as it interacts with a variety of
surfaces (reflecting, refracting, absorbing). • Light can be observed as traveling in a straight line until
it strikes an object. Light can be reflected by a shiny object (e.g., mirror, spoon), refracted by a lens (e.g., magnifying glass, eyeglasses) or absorbed by an object (e.g., dark surface). Questions posed about the behavior and interaction of light with a variety of surfaces, can be explored through investigations using simple equipment.
Vocabulary
• Prism – a solid object that bends (refracts) light.
• Visible spectrum – The range of light energy that people can see– Remember ROY G BIV– Red, orange, yellow, green, blue, indigo, and
violet
Real Life Application
• Have you ever seen a rainbow?
• Have you ever wondered what causes a rainbow?
Facts about Light
• What color is the sun?• Actually, sunlight is a mixture of all the colors of
the rainbow. – White is the color of all the sun’s colors mixed
together.
• Different colors of light travel at different speeds in water and in glass. – So when white light moves from air to glass or from
air to water, the different colors of light bend at different angles and separate into each individual color.
Prisms• A prism is a solid object
that bends light.– When white light hits a
prism, each color of light bends at a different angle.
– Red light is bent the least.
– Blue light is bent the most.
– The light that passes through a prism separates into a rainbow.
Visible Spectrum
• The visible spectrum is made up of all the colors of light that people can see.– These colors are red,
orange, yellow, green, blue, indigo, and violet.
Rainbows
• You can sometimes see a rainbow in the sky during a summer rain when the sun is out.
• Because of the way the raindrops refract and reflect white sunlight, you can see a rainbow only when the sun is behind you.
Rainbows Cont’d
• Each drop of falling water in a rainstorm is like a tiny prism and mirror.
• Sunlight enters a drop, is reflected from the back wall, and then passes out through the front. So, it is refracted twice just as it is in a prism.
Rainbows Cont’d
• There are more colors in a rainbow than anyone could count, however, most people use just seven to remember the order in which the bands always appear: red, orange, yellow, green, blue, indigo, and violet.
Adding Colors
• A prism breaks white light into colors. • You can also add colors together. • When you add different colored lights together,
they form other colors. – Shining a red light and a green light onto the same
spot will make a yellow light. – Shining a blue light and a red light onto the same spot
will make a purple light.– You can add red light, blue light, and green light in
different ways to make all other colors.
Adding Colors
• Televisions and computer monitors add light colors. – The inside of a TV screen is coated with
millions of tiny dots of red, green, and blue. – Dots that are near each other are made to
glow in different patterns and brightnesses. – Your eyes combine the colors to make the
pictures you see.
Seeing Colors
• All the colors of light, called white light, hit every object you see.
• Most objects absorb most of the light, but not all of it.
Seeing Colors Cont’d
• Mixing paint colors is a way of controlling absorption and reflection. – Yellow paint reflects yellows and absorbs other
colors. – Blue paint reflects blues and absorbs other colors.
• When you mix yellow and blue, all the other colors are absorbed except greens.– So, you see shades of green when you mix blue and
yellow paint.
• When you mix all paint colors, almost all light is absorbed, so you see black.
Ticket Out the Door
1. Describe how a prism works.
2. Name the colors that make up white light.
3. Which light colors are absorbed and which are reflected by a yellow tulip?