Fish washed ......

Demonstrate resonance phenomenon.

Experimental device

Fish washbasin.

Experimental principle

When "ear washing" is rubbed by hand, "fish washing" will vibrate with the frequency of rubbing. When the vibration frequency caused by friction is equal to or close to the natural frequency of the vibration of the "fish wash" wall, the "fish wash" wall resonates and the amplitude increases sharply. However, due to the limitation of the bottom of the "fish wash" basin, the waves generated by it cannot propagate outward, so the incident waves and reflected waves overlap each other on the wall of the "fish wash" basin to form a standing wave. The point with the largest amplitude in a standing wave is called an antinode, and the point with the smallest amplitude is called a node. Rubbing a circular basin-shaped object by hand is most likely to produce a low-value resonance frequency, that is, a vibration form consisting of four antinodes and four nodes. The place with the largest amplitude on the "fish washing wall" will immediately stir the water surface, and the nearby water will be excited to form a spray. When four antinodes act at the same time, there will be splash. Consciously throw four fish in the four places with the largest amplitude on the "fish washing wall", and the spray is like spraying from the fish's mouth.

Experimental operations and phenomena

In the experiment, put a proper amount of water in the "fish washing" basin, wash your hands with soap, and then rub the top of the "fish washing" ear with your hand. When the hands are rubbed synchronously, the "fish washing" basin will make a pleasant hum, and water droplets will be ejected from four parts. When the sound is loud enough, there will be a splash. If you continue to rub your ears with your hands, the water will splash high, just like a fish spraying water.