Electromagnetic Waves Mr. Ahearn The Nature of Electromagnetic Waves Electromagnetic Waves A. ____________________travel through empty space or through matter and is produced by charged particles that.
Download ReportTranscript Electromagnetic Waves Mr. Ahearn The Nature of Electromagnetic Waves Electromagnetic Waves A. ____________________travel through empty space or through matter and is produced by charged particles that.
Electromagnetic Waves Mr. Ahearn 2010 The Nature of Electromagnetic Waves Electromagnetic Waves A. ____________________travel through empty space or through matter and is produced by charged particles that are in motion. Forces and Fields B. An electromagnetic wave is made of two Force fields —an electric field and a _____ magnetic field. ***A force field enables an object to exert forces on other objects, even though they are not touching.*** Forces and Fields Force 1. Earth’s gravity field exerts a _____on all objects and extends out into space Magnetic Fields Magnetic Field exerts a force on 2. A _______________ other magnets, causing them to line up along the direction of the magnetic field. Electric Fields Electric Field 3. The _____________ surrounding a charged particle exerts a force on all other charged particles in the field. Moving charged particle is surrounded a. A _______ by an electric field and a magnetic field. b. As a charged particle moves up and down, Wave it produces an electromagnetic _____. Making Electromagnetic Waves • Electromagnetic waves are produced by charged particles, such as electrons, that move back and forth or vibrate. • As a charged particle vibrates by moving up and down or back and forth, it produces changing electric and magnetic fields that move away from the vibrating charge in many directions. These changing fields traveling in many directions form an electromagnetic wave Properties of Electromagnetic Waves Wavelength C. Electromagnetic waves have a __________ Frequency and a __________. 1. One complete vibration of the charged particle up and down creates one Wavelength _________in an electromagnet. Wavelength that pass by a 2. The number of __________ point in 1 second is the frequency of the electromagnetic wave. Radiant Energy D. Radiant energy- energy carried by an electromagnetic wave. 1. The amt. of energy carried by an electromagnetic wave is determined by its Frequency ___________. More 2. The higher the frequency, the ______energy the EM wave has. The Speed of Light E. Electromagnetic waves travel at the 300,000 speed of light, _________ km/s, in space. • Even though light travels incredibly fast, stars other than the Sun are so far away that it takes years for the light they emit to reach Earth. Questions 1 A gravitational field surrounds _______. A. all objects B. objects the size of Earth C. objects bigger than Earth D. objects bigger than the Sun Question 2 A _______ wave can’t travel through space from the Sun to the Earth, but an _______ wave can. A. compressional, electromagnetic B. electromagnetic, mechanical C. mechanical, electromagnetic D. transverse, sound Question 3 What speed do all electromagnetic waves travel at? Electromagnetic Waves— Classifying Electromagnetic Waves A. Electromagnetic waves have a series of different frequencies and wavelengths Electromagnetic Spectrum called the ___________________. Electromagnetic Waves— Classifying Electromagnetic Waves 1. For waves that travel with the same speed, wavelength increases as frequency decreases ____________. wavelength 2. Radiant energy decreases as ___________ increases. Radio Waves B. ___________ have the lowest frequency and carry the least energy. (wavelength longer than 0.3 m) 1. AM and FM radio signals and T.V. signals are types of radio waves; they can be sent with radio waves using a transmitting and receiving antenna. Radio Waves a. One way to make radio waves is to make electrons vibrate up and down in a piece of metal called an antenna. b. The radio waves from a transmitting _____________ antenna can cause electrons in another piece of metal, such as a receiving antenna, to move up and down, creating an alternating current. Radio Waves Current C. The ________ can be used to produce sound from a loudspeaker, allowing for the transmission of music, television shows, and telephone signals. Microwaves Microwaves have a higher frequency and 2. __________ shorter wavelength than radio waves; they are used for some phone calls and to heat food. (wavelengths b/w about 0.3 m and 0.001 m) Radar 3. ______ Radar uses electromagnetic waves to locate objects by measuring the time it takes for the waves to reach the object, be reflected, and return. Infrared Waves Infrared Waves C. ______________ have wavelengths between one thousandth and 0.7 millionths of a meter and feel warm or hot. detectors 1. Infrared _________ sense objects that are warmer or colder than their environment; TV and VCR remotes also use I.R. waves. 2. Some animals, such as piranhas and rattlesnakes, can detect I.R. waves, which helps them find prey Visible Light Visible Light D. _____________ has wavelengths between 0.7 and 0.4 millionths of a meter. 1. what you see as different colors are EM wavelengths waves of different _____________. longest wavelength 2. Red light has the ________ (low freq.); blue light has the _________ shortest wavelength (high freq.). Ultraviolet Radiation Ultraviolet Radiation E. ___________________ is higher frequency and has shorter wavelength than visible light. 1. Too much exposure to ultraviolet radiation from the Sun can cause sunburn and other health problems. 2. Since U.V. radiation can kill cells, it is sometimes sterilize used to _____________equipment. Ozone Layer 3. The ______________ in Earth’s upper atmosphere helps protect the surface by absorbing much of the Sun’s U.V. radiation. Sun Ultraviolet Light Box • Much of the ultraviolet radiation arriving at Earth is absorbed in the upper atmosphere by ozone. • Ozone is a molecule that has three oxygen atoms and is formed high in the Earth’s atmosphere • Chemical compounds called CFCs, which are used in air conditioners and refrigerators, can react with ozone molecules and break them apart X Rays and Gamma Rays X-rays and ___________, Gamma Rays with even higher F. ______ frequencies than U.V., can go right through skin and muscles. 1. Too much exposure to X-rays or gamma rays can damage or kill cells. Medical Diagnosis if used 2. X-rays are useful in ________________ with appropriate precautions. 3. Gamma rays, which have the highest frequency, can be used to treat Cancerous _____________ Tumors and to kill bacteria in food. Geminga Pulsar Crab Nebula Pulsar Satellites astronomical G. Some ___________ objects emit no visible infrared light but are known through ________ and radio outside images; satellite observations _______ Earth’s atmosphere help scientist study space at wavelengths that do not reach Earth’s surface.