AS Level 7.2 Waves Teaching Notes PDF

**AS LEVEL 7.2 Waves** 1. Graphical representation 1. X takes the distance along the wave. (Displacement of each mass along the wave at a given moment) Draw a distance displacement graph curve in case of transverse wave and \... ①The Y-axis is displacement of a particle. ②The X-ax...

**AS LEVEL 7.2 Waves** 1. Graphical representation 1. X takes the distance along the wave. (Displacement of each mass along the wave at a given moment) Draw a distance displacement graph curve in case of transverse wave and \... ①The Y-axis is displacement of a particle. ②The X-axis is distance along the wave。 ③Amplitude: maximum displacement. ④Wavelength: the maximum displacement of a particle in the wave from its rest/equilibrium position. ⑤cycle (oscillation): The motion of any particle in the wave from the maximum positive displacement (a crest) to a maximum negative displacement (a trough) back to a maximum positive displacement 2. X takes the time of the particle\'s vibrational motion (a particular particle, his displacement versus time)  ①Period T of the wave: the wave repeats itself, in this case after a certain interval of time. This is the time for one complete cycle or oscillation. ②Frequency: The number of oscillations (cycles) per unit time is called the frequency f of the wave. 2. Wave equation 3. Relationship between speed, wavelength, period and frequency Period is measured in seconds (s). Frequency has the unit per second () or hertz (Hz). The period. 4. Distance traveled after time T When the motion time, the distance traveled by the particle is A. When the motion time, the distance traveled by the particle is 2A. When the motion time, the distance traveled by the particle is 3A. When the motion time, the distance traveled by the particle is 4A. 5. Amount of speed to be memorized a\. In a vacuum, the speed of both light and electromagnetic waves is b\. The wave speed for sound in air at atmospheric pressure of Pa and a temperature of 0 °C is about 330. 6. Velocity changes, frequency stays the same Electromagnetic waves decrease in speed as they enter a medium (e.g., water, air, glass, etc.). The propagation speed (**v**) of an electromagnetic wave in a medium is related to its speed **c** in a vacuum and the refractive index **n** of the medium by the relationship: Whether it is an electromagnetic or mechanical wave, the frequency of the propagation process will always remain the same while the wavelength and speed will change when it enters from one medium to another. 7. Frequency changes, speed stays the same 3. CRO-Measuring frequency Measure the frequency of sound waves using a cathode-ray oscilloscope (CRO). 声波转换：麦克风将声波转换为具有相同频率的可变电压。 电压显示：转换后的电压在CRO屏幕上显示。 CRO功能：CRO可以看作是一种能够显示快速变化电压的伏特表。它的光点以由时 间基控制设定的恒定速度在屏幕上移动，同时根据输入电压上下移动。 屏幕显示：屏幕上的显示是变化电压（垂直）y轴与时间（水平）x轴的图形。 频率测量：如果已知水平尺度，可以通过测量周期来确定声波的频率。 Time-base: ()or() Amplitude: (V) 4. Phase difference be in phase: Two particles that vibrate together phase difference: A term used to compare the displacements and relative motions of particles in a wave. phase difference: 5. Wave energy 这些粒子只会围绕一个固定点振荡。来传递能量。每个粒子通过振动；推动它的下一个粒子，将能量传递给它。然后，这个粒子推动它的下一个，不断重复。通过这种方式，能量从一个粒子传递到另一个粒子，再传递到下一个粒子等。 Intensity is measured in watts per square meter ()  So, if one wave has twice the amplitude of another, it has four times the intensity. So, if the amplitude of one wave is **[n]** times the amplitude of another, then its intensity is [ ] times the other.