Wave in time domain and space domain 空間 位置 z 時間 z=0
Compression Rarefaction Intensity Frequency Simple sinusoidal (sin) vibration– pure tone Speed of sound at 20℃, in air 3.3×10 4 cm/sec in water 1.4×10 5 cm/sec Total pressure P P a : ambient air pressure P o : maximum pressure change due to the sound wave Intensity I ~ I : amount of energy transmitted by a sinusoidal sound wave per unit time through each unit area ⊥ the direction of sound propagation ρ: density of medium
Ch12.2 Some properties of waves Ch12.2.1 Reflection and refraction
Ch12.2.2 Interference In phase Constructive interference Out of phase Deconstructive interference R=A+B Same frequency
Car moving wavefront profile change 右邊的人聽到的 :
Car stop wavefront profile did not change 右邊的人聽到的 :
利用超音波及都卜勒效應 量測生物體內液體流速 Urone, College Physics Ex16.7 A diagnostic ultrasound echo is reflected from moving blood and returns with a frequency 500Hz higher than its original 2MHz.The speed of the ultrasound is 1540m/s. (a)What is the velocity of the blood? (b) What frequency does the blood receive?