EM Waves
Physics · विद्युत चुंबकीय तरंगें · 15 facts
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EM waves: accelerating charges produce; no medium needed
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All travel at 3x10^8 m/s in vacuum
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Spectrum: Radio<Microwave<IR<Visible<UV<X-ray<Gamma (increasing freq)
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Radio: communication, TV; longest wavelength
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Microwaves: oven, radar, satellite, mobile
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Infrared: heat; TV remote, thermal imaging
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Visible: only EM eyes see; VIBGYOR
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UV: sunburn; ozone blocks most from Sun
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X-rays: medical imaging, security; penetrate soft tissue
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Gamma: highest energy; nuclear reactions; most penetrating
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Maxwell predicted(1865); Hertz proved(1887)
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Visible: 400nm(violet) to 700nm(red)
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EM waves are transverse; E and B fields perpendicular
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Wi-Fi: 2.4GHz and 5GHz; mobile uses microwaves
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Greenhouse: IR trapped by CO2 causing global warming