Every time a rock is thrown into a river, it pushes the water out of its way, and that creates a ripple from where it has landed. When water is in its calmest, lowest state, it has a flat surface. However, throwing a rock into the river or any other object causes the water to move around, which spreads out the energy. This follows a very powerful principle of physics that says everything seeks to find a state where its energy is as low as possible. One way in which energy can move around is by forming waves. A stone, when dropped in a pond, generates waves in a beautiful pattern that is in the shape of a rippling ring that would radiate outward. These ripples produced, or the water waves that are formed at the surface of the water in a pond, are also called “transverse waves.” This is because, in a water wave, the water molecules move up and down in a vertical direction when the water travels in a horizontal direction along with the water surface. This is the same reason why a cork or a leaf, when placed on the water’s surface, moves up and down in the same place as the water will move across the surface of the pond. 

The Scientific Phenomenon Behind Ripples

You may already know the fact that everything you touch is made up of several tiny molecules. These are made up of even smaller parts that are called “atoms.” Water is also made up of these molecules. However, during a ripple, as explained above, the water molecules do not move away from the rock that has been thrown into the water. The molecules, instead, move up and down. During this up and down movement, when these molecules move up, they drag the other molecules surrounding them up, and when they move down, they drag the other molecules down that are next to them. This is what causes the peaks and troughs. Every time a transverse wave travels horizontally in a medium, it causes the medium particles to vibrate up and down vertically. The ripple that travels away from the rock thrown in the water is much like a human wave that forms in the stadiums. This outward movement starts from the center and then gets quietened down eventually. This expanding ring is called the “wave packet.” 


What is a Wave Packet?

A wave packet is basically a case where two or more waves exist simultaneously. These wave packets are commonly referred to as “wave groups.” The wave packet can also be assumed to be the product of two waves. Wave packets are used to describe how the particles behave. Individually, these different rings travel at different speeds. The long rings travel the fastest, and short ones the slowest. The amplitude, however, is greatest where the waves constructively interact with each other to produce the peak of the wave packet mentioned above. The speed of this peak described here is the velocity of the group, and you can see the individual waves passing through this peak.

The reason why these ripples get smaller and eventually stop is simple. The process of dragging the neighboring water molecules up and down is hard work, and because of this, it slowly uses up all the energy. The ripples thus use up all the energy from the splash and the rock and eventually shrink until you can no longer see them. These ripples often spread in a circular form; however, this is not the only possibility. For instance, if you throw a stick into the water, you may observe straight ripples on the side and round ripples near the end. Thus, we can conclude that rocks made a circular ripple because the rock itself was shaped like that.

Some More Examples

Light waves are also similar to the ripples in the water. This is because they tend to have the same velocity. A lightwave is an example of an electromagnetic wave, and in addition to that, it is also a transverse wave. It can also be refracted, diffracted, reflected, or polarized. The water waves also have similar features. One way in which energy can move around is by forming waves. The waves that we see at beaches are also formed by the energy of the wind. Light and sound also move in waves. The ripples that we see in the water are actually small waves that carry away the energy from where the rock was thrown.

The wave equation helps to explain this concept as well as the cause of ripples in ponds. Read some more articles about other physics equations and concepts on the BYJU’S FutureSchool blogs. 

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