• An introduction to light for my fourth grade science students by Mrs. McColgan
What Is Light?What is visible light How do lightand what are some of its sources? waves act?
What is visible light andwhat are some of its sources? • Visible light is a form of energy, that can be seen. • Sources are the sun, stars, electric lights, fire…
How does light act? Light moves Light can moveLight moves in a straight line through in waves. away empty space. from its source.
How does light act?• Light moves in waves.• Different colors of light have different wavelengths.• Other forms of energy have waves, but they can’t be seen.
• VISIBLE SPECTRUM= Light energy that can be seen• White light can be broken into the colors of the rainbow.• R ed, O range, Y ellow, G reen, B lue, I ndigo, V iolet• ROY G BIV helps us remember the colors of the visible spectrum from longest to shortest wavelength.
Light moves in straight linesaway from its source. • Light does not go around corners • Therefore, we cannot see around corners.
How DoesLight Help Us SeeObjects?• Light travels to an object and then travels from the object to our eyes.• In order for us to see an object there needs to be a straight path of light from the object to our eyes.
Review• What is light?• What are its sources?• How does light travel?• How are light waves measured?• What is the visible spectrum?• What are the colors of white light?
What Happens WhenLight Hits an Object?? • That depends on the material the object is made of.
What happens when light hits an object?• Some objects reflect,or bounce light back
When light hits smooth,shiny surfaces…. • It reflects off at the same angle it hits them, like a ball bouncing off a wall. • So.. we see a clear image in a flat mirror, or other smooth, shiny surface.
When light hitssmooth, shinysurfaces…• The surface reflects more light than it absorbs.• Therefore, we see a clear image.
What happens whenlight hits black orwhite objects?• Black objects absorb light, and don’t reflect any colors of light.• White objects reflect all the colors of the spectrum.
What Happens WhenLight Hits Transparentor Translucent Objects? • Some materials transmit light, or allow light to pass through them, and us to see through them as well • Trans– a prefix meaning through, over, or across
Transparent Materials• Allow light to pass through so whatever is behind can be seen clearly• Name some examples of transparent materials
Translucent Materials • Allow light to pass through, but scatter it so that whatever is behind them can be seen, but not clearly • What are some materials that scatter light, and blur the image??
Seeing the Color ofTransparentor Translucent Objects• Transparent or translucent objects are the color of the light they transmit, or let through.• They absorb all of the other colors.• Blue glass lets blue light pass through it.
What Happens WhenLight Moves from OneMaterial to Another? • Light bends when it moves from one material to another • This is called refraction
Just as you slowdown when you runinto water, lightslows down. •
Refraction • The water bends the light, so the fork appears to be in a different place.
What Happens WhenLight Hits a Lens?• When light hits a lens, a transparent object with a curved surface, it bends the light.• Depending on the lens, objects can be made to appear larger or smaller.
Concave Lenses• Concave lenses are thinner in the middle, and make the object look smaller.
Convex Lenses• Convex lenses are thicker in the middle and make objects appear larger.
Special thanks to…•Phil Collins, Dance into the Light Dedicated to• www.google.com/images my 4th grade•Madonna, Ray of Light science students.