Characteristics of EM Waves Chapter 7

Science Starters for Tuesday, January 17, 2017 The energy transferred by electromagnetic waves is called _____. The _____ occurs when light hits a certain metal and causes electrons in that metal to move. A(n) _____ is a particle of light energy. Light that passes through a polarizing filter is called _____. A(n) _____ consists of changing electric and magnetic fields.

Science Starters for Wednesday, January 18, 2017 List the waves on the electromagnetic spectrum in order of decreasing wavelength.

Science Starters for Thursday, January 19, 2017 Three colors that can combine to make any other color are called _____ colors. When two primary colors combine in equal amounts, they produce a ____ color. Any two colors that combine to form white light are called _____ colors.

Science Starters for Thursday, January 28, 2016 Get a computer and log in THEN answer the following question: Cameron shines green light on a red apple. He then records the color that the apple appears. The red apple appears ____ in color because…

Science Starters for Friday, January 29, 2016 Write test on Friday’s square on the science starter and pass it to the center aisle. Also send your color lab & 2 packets of notes to the center aisle in three separate piles. KEEP YOUR 16-BLOCKS. Study quietly until the test starts.

Characteristics of Electromagnetic Waves An electromagnetic wave is a transverse wave that involves the transfer of electric and magnetic energy. An electromagnetic wave is made up of vibrating electric and magnetic fields that move through space or some medium at the speed of light.

Energy The energy that electromagnetic waves transfer through matter or space is called electromagnetic radiation. Electromagnetic waves do not require a medium such as air, so they can transfer energy through a vacuum, or empty space.

What Models Explain How Electromagnetic Waves Behave? Two different models are needed to explain the behavior of electromagnetic waves: Wave model Particle model

Wave Model of Light An ordinary beam of light consists of waves that vibrate in all directions. Light that has been filtered so that all of its waves are parallel to each other is called polarized light.

Particle Model of Light The ejection of electrons from a substance when light is shined on it is the photoelectric effect. Imagine that light is a stream of tiny particles or packets of light energy, called photons. Enough energy must be used to knock an electron from the metal.  

How Do Electromagnetic Waves Compare? All electromagnetic waves travel at the same speed in a vacuum, but they have different wavelengths and different frequencies. Visible light is the only range of wavelengths your eyes can see. Your radio detects radio waves, which have much longer wavelengths. X-rays have shorter waves than visible light.

What Makes Up the Electromagnetic Spectrum? The complete range of electromagnetic waves placed in order of increasing frequency is called the electromagnetic spectrum. The electromagnetic spectrum is made up of radio waves, microwaves, infrared waves, visible light, ultraviolet waves, x-rays, and gamma rays.

Radio Waves Longest wavelengths Lowest frequency Used in broadcasting to carry signals for radio programs

Microwaves Shorter wavelengths than radio waves Higher frequency than radio waves Cook food Cellular communication Radar – Radio Detection and Ranging Radar is a system that uses reflected microwaves to detect objects and measure their distance and speed.

Infrared Waves The invisible heat you feel. Shorter wavelengths than microwaves. Higher frequency than microwaves. Most objects give off some infrared rays. Warmer objects give off more energy with higher frequencies. Cooler objects give off less energy with lower frequencies. Thermogram- an image that shows regions of different temperatures in different colors.

Visible Light Electromagnetic waves that you can see. Small part of the electromagnetic spectrum. Shorter wavelengths than infrared waves. Higher frequency than infrared waves. Appears white in color when it is actually a mixture of many colors.

Ultraviolet Waves Wavelengths just shorter than visible light. Higher frequency than visible light, so they carry more energy. Too much exposure can burn skin. Cause skin to create vitamin D, which is needed for healthy bones and teeth.

X-rays Wavelengths just shorter than those of ultraviolet waves. Frequency is a little higher than ultraviolet rays, but carry more energy than ultraviolet rays which means they can penetrate most matter. Used to make images of bones and teeth. Too much exposure can cause cancer.

Gamma Rays Shortest wavelengths Highest frequency Have the most energy of all electromagnetic waves

Light and Color Most materials can be classified as Transparent Translucent Opaque

Transparent A material that transmits most of the light that strikes it. You can see through it. The color of the object is the color of the light it transmits.

Translucent A material that scatters the light that passes through it. You can see through it, but the details are blurred. The color of the object is the color of the light it transmits.

Opaque A material that reflects or absorbs all of the light that strikes it. You cannot see through it. The color of the object is the color of light it reflects.

Primary Colors Three colors that can combine to make any other color Red Green Blue When the three primary colors are combined in equal amounts, they produce white.

Secondary Colors Two primary colors combined in equal amounts. Magenta Cyan Yellow

Complementary Colors Any two colors that combine to form white light.

Pigments Colored substances contained in inks, paints, and dyes. When three primary colors of pigments are combined in equal amounts, they produce black They absorb some colors and reflect others – the color you see is the result of the colors that the pigment reflects.