HW # Lim Myeong Jun

 Electromagnetic Spectrum  Radiation Thermometer

 1. Audio frequency (20~20,000Hz) L = 10,000km λ : Wave length c : Speed of light f : Frequency

 2. Radio frequency  2-1. Low frequency : 30kHz ~ 300kHz (10km ~ 1km)  2-2. Medium frequency : 300kHz ~ 3MHz (1km ~ 100m)  2-3. High frequency : 3MHz ~ 30MHz (100m ~ 10m)  2-4. Very high frequency : 30MHz ~ 300MHz (10m ~ 1m)  2-5. Ultra high frequency : 300MHz ~ 3GHz (1m ~ 0.1m)

Length of antenna = λ/2 One of the most important reason for using high frequency signal is that can reducing antenna length. c = 3.8x10 8 m/s Vs(t) t t Time delay : 1/3x10 -7 s L = 10m

 3. Microwave  3-1. Centimeter wave : 3GHz ~ 30GHz (10cm ~ 1cm)  3-2. Millimeter wave : 30GHz ~ 300GHz (1cm ~ 1mm)  3-3. Sub millimeter wave : 300GHz ~ 3THz (1mm ~ 0.1mm)

 4. Infrared  4-1. Far infrared : m ~ m (100um ~ 10um)  4-2. (Intermediate) infrared : m ~ m (10um ~ 1um)

 5. Visible light : ~nm Red : Longest λ … Violet : Shortest λ

 6. UV(Ultra violet)  7. X-ray  8. γ-ray Frequency ↑ ∝ Energy ↑ E : Energy h : Plank constant ν : Frequency

Visible light Micro wave (Infrared) Red has long λ and Blue has short λ Micro wave (Infrared) Although we can’t see the light(micro wave), all of the object radiate micro wave

Fig. Radiation Thermometer Op-amp ADC mp LCD Battery Shutter Lense IR sensor (Pyroelectric sensor) -> No dc response Sensor Input Sensor Output a : Shutter on b : Shutter off a b