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Published byAnnis Boyd Modified over 9 years ago
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Electromagnetic spectrum Dept. of Biomedical Engineering 2003200449 YOUNHO HONG
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Electromagnetic spectrum (1)Audio frequency : 20Hz ~ 20,000Hz (2) Radio frequency (2-1) Low frequency : 30kHz(10km) ~ 300kHz(1km) (2-2) Medium frequency : 300kHz(1km) ~ 3MHz(100m) (2-3) High frequency : 3MHz(100m) ~ 30MHz(10m) Speed of light frequency Wave length Ex) 30Hz => (Diameter of the earth) Wave length is too long for making differences
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Electromagnetic spectrum Vs Vo send off the data through the air. wave length x =0m x =10m t 10 -10 t 10 -10 delayed by this time (1 period)
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(2-4) Very high freq.(VHF) : 30MHz(10m) ~ 300MHz(1m) (2-5) Ultra high freq.(UHF) : 300MHz(1m) ~ 3GHz(0.1m) (3) Microwave (3-1) Centimeter wave : 3GHz(10cm) ~ 30GHz(1cm) (3-2) Millimeter wave : 30GHz(10mm) ~ 300GHz(1mm) (3-3) Submillimeter wave : 300GHz ~ 3THz(0.1mm) Electromagnetic spectrum Why is high frequency usually used? - Because of length of antenna These are not very often used because of tech. problem
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(4) Infrared (4-1) Far infrared : 100um ~ 10um (4-2) (Intermediate) Infrared : 10um ~ 1um (5) Visible light : ~nm Red (longest λ) ….. Violet (shortest λ) (6) Ultra violet (7) X-ray (8) r-ray Electromagnetic spectrum Plank constant energyfrequency
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Electromagnetic spectrum Red.. Yellow Green.. violet λ is longer. freq. is lower. absolute temperature If you know one of them, You can get the other.
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Radiation Thermister IR LCDLCD amp ADC MP infrared shutter lens switch pyroelectric sensor IR sensor has no DC response. Resistance of IR is changed while the quantity of infrared changes.
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Thank You.
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