Science 10 Second Quarter Electromagnetic Waves PDF

THE NATURE OF ELECTROMAGNETIC WAVES molecules move and vibrate, the hotter it becomes. This heat is then emitted from the JAMES CLERK MAXWELL object as thermal ener...

THE NATURE OF ELECTROMAGNETIC WAVES molecules move and vibrate, the hotter it becomes. This heat is then emitted from the JAMES CLERK MAXWELL object as thermal energy. ‣ Scottish Physicist ‣ The Father of ‣ DIFFRACTION is the Electromagnetic Theory bending and spreading of - Maxwell Formula - waves around an obstacle. A Electricity and Magnetism spectrometer uses diffraction to separate light into a range of wavelengths, such as a spectrum. ‣ SCATTERING occurs when light bounces off an object in ELECTROMAGNETIC SPECTRUM a variety of directions. The The entire range of EM waves in order of amount of scattering that increasing frequency and decreasing takes place depends on the wavelength light's wavelength and the WAVE FREQUENCY object's size and structure A disturbance in space Number of waves produced in one second ‣ The higher the frequency, the more energy the CREST WAVELENGTH wave Highest point in a wave Distance between two ‣ EM waves do not require a media in which to identical two successive travel or move identical parts of a wave ‣ EM waves are considered to be transverse waves because they are made of vibrating electric and TROUGH RANGE magnetic fields at right angles to each other, and The lowest point in a The extent of or the to the direction the waves are travelling wave limits between which ‣ There is an inverse relationship between wave variation is possible size and frequency: as wavelengths get smaller, frequencies get higher ELECTROMAGNETIC SPECTRUM EM ENERGY The terms light, em waves, and radiation all refer to the same physical THE WAVES (IN ORDER) phenomenon: EM energy RADIO Can be described by frequency, wavelength, They have the longest wavelengths and the or energy lowest frequencies; wavelengths range from WAVE BEHAVIOURS 1000s of meters to 0.001 m Used in: RADAR (radio detection and ranging), ‣ REFLECTION is when cooking food, satellite transmissions incident light (incoming INFRARED WAVES (HEAT) light) hits an object and Have a shorter wavelength, from 0.001 m to bounces off. Very smooth 700 nm, and therefore, a higher frequency surfaces such as mirrors Used for finding people in the dark and reflect almost all incident airports light. VISIBLE LIGHT Wavelengths range from 700 nm (red) to 30 ‣ ABSORPTION occurs nm (violet) with frequencies higher than when photons from infrared waves. incident light hit atoms These are the waves in the EM spectrum that and molecules and cause humans can see them to vibrate. The Visible light is a very small part of the EM more an object's spectrum ULTRAVIOLET LIGHT thermometer, which Wavelengths range from 400 nm to 10 nm; the expanded the known frequency (and therefore the energy) is high range of the enough with UV rays to penetrate living cells electromagnetic and cause them damage spectrum. Bees, bats, small rodents, and birds can see Wilhelm Conrad Discovered X-rays in UV light Roentgen 1895, a high-frequency UV produces vitamin D in our bodies. form of electromagnetic However, too much can lead to sunburn and radiation, which has cancer become essential in X-RAY medical imaging and Wavelengths from 10 nm to 0.001 nm. These scientific research. rays have enough energy to penetrate deep Plato While Plato didn’t into tissues and cause damage to cells; are contribute directly to stopped by dense materials such as bone. EMS, his philosophical Used to look at solid structures discussions about the GAMMA RAYS nature of reality and Carry the most energy and have the shortest perception laid some groundwork for later wavelengths, less than one trillionth of a meter thinking about light and −12 (10 ). optics. Gamma rays have enough energy to go Pythagoras Pythagoras is known for through most materials easily; you would need his work on harmonics 3-4 ft thick concrete to stop theme and sound waves, which, Gamma rays are released by nuclear reactions though not in nuclear plants, by nuclear bombs, and by electromagnetic waves, naturally occurring elements on earth provided early thinking Sometimes used in the treatment of cancers about wave phenomena CONTRIBUTION ON EMS that are essential for understanding EMS. PEOPLE CONTRIBUTION Empedocles Proposed the idea that light travels as a wave Thomas Young Demonstrated the wave and has a finite speed, nature of light through his which was foundational in famous double-slit the conceptual experiment, showing that development of wave light interferes, an theories of light and, important concept in eventually, the understanding the electromagnetic behavior of spectrum. electromagnetic waves. Christiaan Huygens Developed the wave James Clerk Maxwell Formulated Maxwell’s theory of light, which equations, which describe helped explain the the behavior of electric diffraction and refraction and magnetic fields and of light and supported the predicted the existence of idea of light as an electromagnetic waves, electromagnetic wave. forming the theoretical foundation of the Sir Isaac Newton Proposed the particle electromagnetic theory of light and spectrum. studied the dispersion of light through prisms, Sir William Herschel Discovered infrared leading to the radiation in 1800 by understanding of the observing that invisible visible spectrum as part rays beyond red light in of the EMS. the spectrum heated up a Heinrich Hertz Experimentally confirmed speed of light by the existence of observing the motion of electromagnetic waves Jupiter’s moons, predicted by Maxwell by providing an essential producing and detecting piece of evidence in the radio waves, thus development of the wave extending the known theory of light. electromagnetic spectrum. Albert A. Michelson Measured the speed of light with great precision Max Planck Developed quantum through the theory, which explained Michelson-Morley blackbody radiation and experiment, which laid the foundation for provided strong evidence understanding the for the theory of special quantum nature of relativity and helped in electromagnetic understanding the radiation. propagation of electromagnetic waves. Albert Einstein Explained the photoelectric effect, proving that light has both particle-like and wave-like properties (wave-particle duality) and contributed to the development of quantum mechanics and relativity, both crucial for understanding EMS. Arthur Compton Discovered the Compton effect, which showed that X-rays scatter off electrons and behave like particles (photons), reinforcing the quantum theory of electromagnetic radiation. Louis Victor de Broglie Proposed that particles, such as electrons, also have wave properties, extending the wave-particle duality to all matter and influencing our understanding of quantum mechanics and the EMS. Galileo Galilei Though Galileo didn’t contribute directly to EMS, his work in astronomy and the speed of light (he attempted to measure it) contributed to later theories about light as part of the electromagnetic spectrum. Ole Rømer First measured the finite THOMAS YOUNG His double-split experiment showed that light can behave as a wave. Made evidence for the wave theory of light pure-wavelength light sent through a pair of vertical slits is diffracted into a pattern on the screen of numerous vertical lines spread out horizontally. WILHELM CONRAD ROENTGEN Discovered x-ray ○ X-rays are a type of high-energy electromagnetic radiation that can pass through most substances, including human tissue, to create shadows of solid objects SIR WILLIAM HERSCHEL Discovered infrared ○ Infrared light is a type of invisible light that exists beyond the visible spectrum of light JAMES CLERK MAXWELL Showed mathematically that EM waves could propagate through free space Constructed and oscillating electrical circuit which showed the changing electric and magnetic fields could produce EM radiation that could travel through a vacuum PLATO Thought that light consisted of streamers emitted by the eye PYTHAGORAS Light originated from luminous bodies in the form of very fine particles EMPEDOCLES Light is composed of high-speed waves of some sort CHRISTIAN HUYGENS Explained the reflection of light using wave motion HEINRICH HERTZ Demonstrated the existence of EM waves that exhibit the same properties as the light LOUIS VICTOR DE BROGLIE Proposed that every particle of matter is somehow endowed with a wave to guide as it travels GALILEO Hypothesized that light had a finite speed ALBERT A. MICHELSON Conducted that the speed of light in an empty space at c is 2.9979 x 10^8 m/s ARTHUR COMPTON Scattering of x-ray ELECTROMAGNETIC WAVE GENERATION ‣ Perpendicular to each other ‣ Oscillating electric and magnetic field VALUES AND FORMULAE SPEED OF LIGHT [C] = 3.00 x 10^8 m/s PLANK’S CONSTANT [H] = 6.626 X 10^-34 Js c = λf [Speed of light = wavelength x frequency] e = hf [Energy = Planks constant x frequency]  LIGHT PROPERTIES OF LIGHT HISTORY Light travels in straight lines ‣ Biblical Account - Genesis: “Let there be light” Light travels very fast ‣ 1000 AD ○ Around 300,000 km per second It was proposed that light consisted of tiny ○ It can go around the world 8 times in particles one second Socrates and Plato theorized that light Light travels much faster than sound traveled from the eyes to the objects one saw ○ Thunder and lightning start at the Followers of Pythagoras believed that light same time but we will see lightning was made up of particles emitted from the first objects rather than from the eyes. We see things because they reflect light into PEOPLE our eyes. ★ ARISTOTLE LUMINOUS AND NON-LUMINOUS OBJECTS ○ Light moves as a wave, light is like LUMINOUS - Objects that produce light ripples on water. ○ The sun, lights, campfires, lamps, ★ LEONARDO DA VINCI lasers ○ Noted similarities between the NON-LUMINOUS - Objects that reflect light behavior of sound and light. ○ The moon, people, mirror, objects ★ NEWTON SHADOW ○ Used this particle model to explain Places where light is blocked reflection and refraction THE RAY MODEL OF LIGHT ★ CHRISTIAN HUYGENS Represented by rays; usually in straight lines ○ Explained many properties of light by REFRACTION REFLECTION proposing light was wave-like Different surface Flat surface ○ 1678 Bending of light The angle of ★ THOMAS YOUNG incidence = angle ○ 1801 of reflection ○ Strong support for wave theory by REFLECTION showing interference The law of reflection states that the angle of ★ AUGUSTIN FRESNEL reflection is equal to the angle of incidence ○ Proposed a comprehensive A ray of light, mathematical wave theory the incident travels in ★ JAMES CLERK MAXWELL a medium ○ 1865 When it ○ Electromagnetic waves travel at the encounters a speed of light boundary with a ★ PLANCK second medium, part ○ EM radiation is quantized of the incident ray is Implies particles reflected back to the ○ Explained light spectrum emitted by first medium. It is directed backwards, into hot objects the first medium in one dimension. ★ EINSTEIN 4 PROPERTIES OF REFLECTION ○ Particle nature of light Reversed ○ Explained the photoelectric effect Same Size SPEED OF LIGHT Same Distance GALILEO Upright ○ Made the first serious attempt to REFRACTION measure the speed of light Bends light or changes direction at the ○ Conducted experiment using lamps boundary between two media FACTS ABOUT LIGHT ○ Example: pencil inside a glass of water 3.00 X 10^8 m/s Light bends, occur because of varying wave Can be: Reflected, absorbed refracted speeds in two media. The index of refraction (n) describes the speed of change, and the speed of a wave in a medium is v = c/n.  Air 1.000 293 The beam of the first medium is called the Carbon Dioxide 1.000 45 incident ray. The incident ray hits the boundary of Oxygen, O2 1.000 271 an angle of incidence. Hydrogen, H2 1.000 73 The beam is the second medium called the refracted ray, the refracted ray leaves at an angle of refraction. SNELLS LAW Describes the relationship between the angle of incidence and angle of refraction The degree to which light is bend depends on the medium and the density of the medium Snell's law states that: the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant. For light, going from a vacuum into another medium, the constant is called the index of refraction EQUATION N = Sin 0i / Sin 0 r - N - index of refraction - 0 i angle of incidence - 0 r - angle of refraction SUBSTANCES SOLIDS AT 20 C Diamond 2.419 2.42 Glass, crown 1.523 1.52 Ice (0 C) 1.309 1.31 Sodium Chloride 1.544 1.54 QUARTZ Crystalline 1.544 1.54 FUSED 1.458 1.46 LIQUIDS AT 20 C Benzene 1.501 1.50 Carbon Disulfide 1.632 1.63 Carbon 1.461 1.46 Tetrachloride Ethyl Alcohol 1.362 1.36 Water 1.33 1.33 GASES AT 0 C, ATM