Presentation on theme: "WHAT IS LIGHT? Light arrives on our planet from the Sun, (93 million miles away). Light travels at 186,000 miles per second, so the light you're seeing."— Presentation transcript:
WHAT IS LIGHT? Light arrives on our planet from the Sun, (93 million miles away). Light travels at 186,000 miles per second, so the light you're seeing now was emitted from the Sun about eight minutes ago. Remember : Light does NOT need a medium to travel through!
Sunlight is not light of just one color—it's what we call white light, made up of all the different colors mixed together. Rainbows appear when light from the sun is refracted (bent) by droplets of water.
When white light is refracted through a prism, you can also see the spectrum of colors.
We see different colors because light energy travels in the form of waves.
The color red has the longest wavelength. Purple has the shortest wavelength. Colors appear differently because they travel with different wavelengths. Visible Light Spectrum: ROYGBIV (Red, Orange, Yellow, Green, Blue, Indigo, Violet)
1.What does ROYGBIV stand for? 2.Which color in the visible light spectrum has the shortest wavelength? 3.Which color in the visible light spectrum has the lowest frequency? Quick Check! Purple Red, Orange, Yellow, Green, Blue, Indigo, Violet Lowest frequency/Longest wavelength: RED
Color is one of the strangest things about light. We see things because sunlight (white light) is reflected off them. So why isn’t everything the same color?
When light hits an object it can be Reflected Absorbed Transmitted The color of an object depends on the color it reflects.
Why does a tomato look red? When sunlight shines on a tomato, the red part of the sunlight (that wavelength) is reflected back again off the tomato's skin, while all the other colors of lights are absorbed (soaked into) the tomato, so you don't see them.
That's also true of a blue book, which reflects only the blue part of sunlight but absorbs light of other colors.
Why is the sky blue? Sunlight reaches Earth's atmosphere and is scattered in all directions by all the gases and particles in the air. Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere.
Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.
There are other types of waves that we cannot see. These waves are too long or short to be visible to us. Notice there is a very small area of the spectrum that is visible light.
Transparent Materials– materials that transmit most of the light through them. Light passes through easily Example: glass, saran wrap, water, etc. Translucent Materials– materials that scatter light through them as the light passes through. Light is blurred Example: cloud
Opaque materials– materials that reflect or absorb all of the light that passes through them. Opaque materials are the color they reflect. Light is blocked Example: aluminum foil, cardboard, etc.
I have 3 different objects. Predict what will happen when I shine a light… On the 1 st object On the 2 nd object On the 3 rd object Observe what actually happens…