What is resonance and resonance effect

Big Bang HTL 3, textbook

Vibrations - Specialization 2 Selected Chapters of Classical Physics (III. Jg., 5th Sem.) 17 You will have the practical implementation of this fact in a shock absorber test. A car is placed on a device with which vibrations can be generated (Fig. 2.22). Then the car is made to vibrate at different frequencies and the amplitude is measured. Even at the resonance frequency, the car must not vibrate too much. Otherwise the shock absorbers are in the bucket and have to be replaced (Fig. 2.23). Liquids and gases can also vibrate and thus also come into resonance. The air column in a bottle, for example, has a very specific natural frequency that depends on its length. When empty, the bottle produces the lowest tone (see also Chapter 3.2, p. 27). When you blow over the bottle, you create all possible frequencies, but the natural frequency of the bottle is amplified the most. That is why you always get the impression of a certain pitch (F13). There are two reasons for joyful singing in the bathtub: reflection and resonance (F14). First, the sound is reflected many times between the nearby walls and does not immediately fizzle out like in a large room. In addition, there is the resonance effect of the vibrating air, which amplifies the voice, similar to the bottle. Info: tidal world record Info: look into the body -> p. 18 To keep a vibration swinging, you need an energy source. Sometimes these energy sources and the vibrating object are directly connected to each other. The oscillation then practically controls itself. In technology, this is called feedback. The oldest example of feedback is the pendulum clock (see Fig. 11.5, NAWI 1). The pendulum or the anchor itself control the energy supply and this inevitably takes place in Fig. 2.22: Each shock absorber can be tested individually on this device - in this picture it is, for example, the right one. Fig. 2.23: Test diagram for shock absorbers: Everything is ok at the rear right, but the front right shock absorber vibrates too much at the resonance frequency and must therefore be replaced. right rhythm. This results in an undamped oscillation - at least until the next wind-up. All string instruments and the car horn also work on the principle of feedback. Info: Tüüüt -> p. 18 You are also familiar with an unpleasant form of feedback from everyday life: the whistling that occurs when you get too close to the loudspeaker with the microphone (F18). But what actually happens there? The microphone captures the sound vibrations and these are amplified through the loudspeaker. Of course, the microphone also “hears” these vibrations, amplifies them again, and so on. This would actually make the sound infinitely loud. Thank goodness no loudspeaker can do that - if it gets too much, it overdrives and starts to whistle. Incidentally, the legendary J IMI H ENDRIX was the first musician to intentionally use the feedback from his electric guitar to make music. Tidal world record Even a liquid can vibrate and therefore has a resonance frequency. If your step frequency just happens to hit this resonance frequency, then the surface of the water can build up and the soup or coffee slosh over (F11). You can prevent this by changing your step frequency. The resonance frequency of a liquid depends on the “container”. It can be a plate, but it can also be an entire bay. The smaller the “container”, the greater the resonance frequency. The difference between ebb and flow in the open ocean is only about half a meter. In the Bay of Fundy in Canada, however, it can be 17 meters on some days. That is a world record! The reason for this is that the bay behaves towards the ocean like a plate to soup. Because the bay is so large, the natural oscillation period is 13 hours. But that almost corresponds to the time between two floods (12.5 hours). The high tide is therefore due to a resonance phenomenon (F12). i Fig. 2.24: Maximum difference between ebb and flow at different points in the Bay of Fundy For testing purposes only - property of the publisher öbv