The amplitude of a wave is a critical property. So, if you want to know, “Does amplitude of wave change?” When, why, and how are these things going to happen? Then go ahead and read.
The energy transported by an electromagnetic wave, an acoustic wave, or any other wave is directly proportional to the amplitude square of that wave. Thus, whenever there is a change in the wave’s energy, then its effect impacts the amplitude of the wave.
Before we go into the depth of our questions, does amplitude of wave change, how, when, and why? Let us first get brief information about the wave and its amplitude.
Wave: In physics, a wave is considered an energy transport phenomenon that transmits energy along with a medium without carrying any matter. As a result, we think of it as a medium disturbance that transports energy but not mass. There are primarily two types of waves, which are listed below:
- 1. Longitudinal: Sound waves
- 2. Transverse: Electromagnetic waves or light waves
Amplitude: The total distance between a wave’s resting position and the maximum displacement it can span is referred to as its amplitude.
Wavelength: The size or length of a single wave is known as its wavelength. It is calculated as the distance or gap between two consecutive peaks.
Frequency: The frequency of a wave tells us how many waves pass by a certain spot in a given amount of time.
If you are considering sound waves, their amplitude determines how loud the sound is. A higher amplitude of a sound wave means its loudness is higher, and a lower amplitude means lower loudness.
When we study a light wave, the amplitude of the wave is nothing but the brightness or intensity of the wave in comparison to other light waves of the same wavelength. Light with a greater amplitude has a greater intensity or brightness, while light with a smaller amplitude has a lesser intensity or brightness.
Now the question is, does amplitude of wave change? Let us see how things turn out.
Does amplitude of wave change?
⇒ The wave’s amplitude is a crucial characteristic.
The amplitude of a wave is not a constant characteristic. As a result, it is subject to change due to situational factors.
When does amplitude of wave change?
⇒ We know that the energy of the wave is always conserved, which means it cannot be destroyed or generated.
Any wave’s frequency and amplitude are independent properties. However, frequency change leads to a change in energy. Thus, the amplitude of every wave, whether longitudinal or transverse, changes with energy in order to conserve the total energy.
Why does amplitude of wave change?
⇒ The amplitude of a wave can vary with the change in energy of the wave.
The wave’s energy and the amplitude of the wave are closely related to each other. The relation between the energy of the wave and the amplitude of the wave is given as below:
E ∝ A2
Where letter E denotes the wave’s energy, and letter A denotes the wave’s amplitude.
We can see that the wave’s energy is directly proportional to the square of the amplitude of the wave. Thus, if there is a slight change in energy, it results in a squared change in amplitude.
We can deduce from the energy and amplitude of wave relationships that if the energy of a wave is large, its amplitude will be high. The amplitude of a low-energy wave will be similar to that of a low-energy wave. Both scenarios are represented in the diagram below.
Thus, we can say that any change in the wave’s energy leads to a change in the wave’s amplitude.
How does amplitude of wave change?
⇒ A change in energy is the most likely cause of the amplitude variation, but it might also be a change in wave speed. The wave’s energy can go up or down.
If you have a wave driver, you can use it to increase the energy and, therefore, the amplitude. However, when a wave travels through a medium, some of the energy is diluted, resulting in a reduction in amplitude. Sometimes it’s not the energy but the change in wave speed that also results in a change in wave amplitude, as seen in the ocean waves.
Let us look at some real-life examples to see what we’re talking about.
We have already discussed in detail that the wave’s amplitude depends on the energy carried by that wave. Now we know that every medium has friction. There is no such thing as a frictionless medium or an ideal medium. As a result, as a wave moves through a medium, it experiences friction. The energy of the wave will dilute as it spreads out in the medium, overcoming the friction of the medium. The loss of energy will result in attenuation or reduction of the amplitude of that wave.
Now one can also increase the amount of energy using the driver of the wave. Here, “wave driver” simply means the consistent work done on that wave. Consider the case of a helical spring that is initially at rest. As you stretch it in a horizontal direction, a transverse wave or pulse is produced. In other words, as you apply force to the spring, it will deviate from its rest position in proportion to the force applied.
To achieve a higher amplitude or maximum displacement, more energy must be applied or more work must be performed. Finally, the energy that a transverse pulse or wave carries across the medium is related to its amplitude. The wavelength, frequency, and speed of a transverse pulse or wave are unaffected by putting a lot of energy into it. The amount of energy applied to a pulse or wave will only change the amplitude of that pulse or wave.
The change in the amplitude of ocean waves is caused by the slowing of the wave speed. Slowing the wave allows energy to be converted into higher amplitude waves since the frequency and energy level carried by the wave cannot change. When watching ocean waves approaching shallower water, this effect is very noticeable. As the propagation speed slows, the wave crests become crowded together. The wave heights or the amplitude increase as a result of the crowding until the wave breaks.
Frequently Asked Questions (FAQs):
Q: Does amplitude change over time?
Ans.: Ideally, the amplitude of the wave should not alter over time. However, as we live in the real world, things are changing.
There is no such thing as a frictionless system in the actual world. As a result, as the wave loses energy, the amplitude of the wave decreases over time. When we study a simple harmonic motion, we can see that the amplitude of the simple harmonic wave decreases exponentially over time.
The following graph represents the damping of the wave over time:
Q.: Does the amplitude of the wave change when the wave changes the medium of propagation?
Ans.: When the wave propagates from one medium to another, some part of the wave goes through the medium, and the remaining part of it will reflect back.
The portion of the wave that goes through the medium signifies the portion of the wave’s energy that has been lost in the medium. Reflected waves are considered the remaining energy. As changing media causes a decrease in energy, it directly leads us towards the change (more precisely, reduction) of amplitude.
Q.: What happens when the amplitude of the wave is doubled?
Ans.: The amplitude of a wave has a direct connection with energy, which is given below:
E ∝ A2
When the amplitude of a wave is doubled, the energy of the wave increases by four times. As a result, doubling the wave’s amplitude signifies quadrupling of the energy transferred by the wave.
Similarly, if the amplitude of a wave is tripled, it implies a nine fold increase in the supply of energy delivered by the wave.
Click here to know how to find the amplitude of a wave.
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