ASTR 1345 1st Edition Lecture 11 Outline of Last Lecture I. GalileoII. Planetary MotionA. Direct MotionB. Retrograde MotionC. Parallax III. ConfigurationsA. ElongationB. OppositionIV. ConjunctionsA. Inferior ConjunctionB. Superior ConjunctionV. Centripetal AccelerationVI. EnergyA. Conservation of EnergyB. Angular MomentumC. Kinetic EnergyD. Potential Energy/Radiative EnergyVII. MatterOutline of Current Lecture I. Electromagnetic Waves/SpectrumII. Wave QuantitiesA. SpeedB. WavelengthC. FrequencyIII. Properties of LightA. ReflectionB. RefractionC. DispersionIV. Light Waves and Finite Speed of LightV. PhotonsVI. Colors and FrequencyCurrent LectureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.l.Electromagnetic waves are electric and magnetic waves that are perpendicular to each other. They are measured by the speed of light (300,000 k/s). A spectrum is the result of electromagnetic radiation passing through a prism or grating so that different wavelengths are separated. The electromagnetic spectrum goes from the longest wavelength and lowest frequency: radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-Rays, and end in the shortest wavelength highest frequency which is gamma rays. Visible Light has a narrow range of wavelengths from 400nm to 700nm.ll.A. Speed is presented with a V and can also be represented as a C for EM waves and it is a constant, the speed of light.B. Wavelength is the distance between two successive peaks in a wave and is measuredin nanometers (nm).C. Frequency is measured in Hertz and it’s the number of peaks or troughs of a wave that pass a fixed point each second. It’s the number of complete vibrations or oscillations per second. V= frequency X wavelength. If frequency increases then wavelength decreases and vice versa.lll.A. Reflection is the rebounding of light rays off a smooth surface.B. Refraction is the bending of light rays when they pass from one transparent medium to another.C. Dispersion is the separation of light into colors.lV.Light waves don’t have to travel through a medium unlike water waves which travel through the liquid medium of water. The first evidence for finite speed of light came in 1675 when Ole Rᴓmer, a Danish astronomer, carefully timed eclipses of Jupiter’s moons. The moment a moon enters Jupiter’s shadow depends on the distance between Earth and Jupiter. V.Photons are a discrete unit of electromagnetic theory. Photon energy equals Planck ’s constant X the Speed of Light divided by wavelength. E=hf which is the energy of a wave= Planck ’s constant X frequency. Vl.The color of light depends on frequency. Violet has the highest frequency at 400nm and the lowest wavelength. Red has the lowest frequency at 700 nm and the highest wavelength. We can see white when it absorbs all the colors and they’re all reflected back when we see black it’sthe opposite, none of the colors are reflected
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