We are actually surrounded by many types of waves. Musical instruments are familiar to us to appreciate the waves of harmony.
A piano can produce high to low pitched sounds. There are typically 88 keys. If a piano has to create the range of frequencies (20 – 200 thousands Hertz) that a human can hear, it will be 120 keys to cover it.
Flute is a musical instrument with both open ends. Clarinet is an instrument with one closed end. The way of resonance for each instrument is different. Therefore, the pitch of the sound will be different even with the same length.
On the other hand, there are sounds that human cannot hear. The ultrasonic wave is one of them. Ultrasonic waves in liquid are used for cleaning by using formation and collapse of voids due to reflected stationary waves.
It is also used for treating diseases by focusing the wave energy at specific parts of the human body. In addition, ultrasonic waves are applied to cause special reactions for chemistry.
Other form of waves from nature is the earthquake. It is inevitable to experience while we are living on the earth.
The period of a large earthquake may become minutes instead of seconds. So the wavelength is as much as several thousand kilometers. This is as if the whole earth is vibrating like a bell.
Water also can make waves in nature. The surface of water waves is moving with circular disturbances. The waves move greatly with the circular motion if it’s close to the surface. On the other hand, they swing with smaller circles when it is deeper. The restoring force of water waves is gravity and surface tension. Surface tension tries to minimize the surface area of water.