Free, forced and damped oscillations

As per the definition of oscillation, it is a repetitive motion about its mean position in physics, commonly in terms of time. Usually, two or more distinct states or central values or equilibrium are used for measuring them. Some of the most common examples that you can find for oscillation are simple pendulums and alternating current. If you are in any way familiar with the topic, you must know that free, forced, and damped oscillations are its popular classifications. And if you are not familiar with it, we will cover everything from governing parameters of oscillation, examples of oscillation and its different types. 

What are the parameters that govern oscillation? 

The simple definition of oscillation is the back and forth movement that repeats in a consistent rhythm. Here are the top three parameters that govern oscillation: 

• Period of oscillation
• Oscillation frequency
• Oscillation amplitude

How can you calculate the parameters of oscillation? 

Following is the formula of parameters that govern oscillation and help in its calculation: 

1. Period of oscillation: 

To mathematically express the period of oscillation for a simple pendulum, we use the following expression.            

Here,

T represents the period of oscillation in sec.

L represents the effective length of a pendulum in meters. 

G means the acceleration due to gravity in the SI unit. 

2. Oscillation frequency:

To mathematically express oscillation frequency, the following expression is used: 

Where F represents the frequency of the oscillation and T represents the period of oscillation.

Unit of frequency is Hz or second inverse.

3. Oscillation amplitude:

The amplitude of the oscillation will be the highest distance away from the equilibrium position (mean position about which oscillation is happening) which is represented by ‘A’.

What are the examples of oscillation? 

One of the most compelling examples of oscillation includes the tuning fork. When a tuning fork strikes against the glass, it follows repeated vibrations. Further, the waves of a vibrating tuning fork travel a certain distance in either direction of its equilibrium position. One more example among the list of examples of oscillation that we can consider is the motion of alternating current. 

What are the different types of oscillation? 

The oscillation has three primary classifications: free, forced, and damped oscillation.  

1. Free Oscillation

Free oscillation contains a consistent period and amplitude without needing any outside force to set it. Generally, free oscillation does not go through damping. But in the region of all-natural systems, the process of damping is observed till the time any consistent outside force emerges to overcome it. In this system, every property remains constant, including frequency, amplitude, and energy. 

Example of free oscillation-

Oscillations of a simple pendulum, oscillations of objects connected to a horizontal spring, sound produced by tuning a fork in short distance etc.

2. Damped Oscillation

Damping refers to a type of friction to oscillation. And damped oscillation refers to the kind of oscillation that gets dull over time. Due to the presence of damping, the oscillation’s amplitude decreases over time.

Due to the system’s energy loss, the amplitude is lessening. Therefore, the system loses energy when it attempts to overcome outside forces, including resistance, friction and many other resistive forces. Thus, when there is a reduction in amplitude, the system’s energy also reduces. Damping is classified into two categories: natural and artificial damping. 

Example of free oscillation-

In practical situations all the oscillation is having some type of friction or air resistance.like oscillations of a simple pendulum with damping force due to air drag.

3. Forced Oscillation

Forced oscillation is when any external periodic force causes the body to oscillate. In this scenario, oscillation amplitude goes through a damping process. However, there are no changes in amplitude, and it remains constant. It is because the system has an external energy supply. 

Example: A bird flapping its wings periodically and repeatedly to achieve a consistent flight is an example of forced oscillation. Its wings move a certain distance from its initial position, then reach the equilibrium position, again flap in the opposite direction to move the similar direction, then again coming to its initial position. 

Conclusion

Oscillation is an essential part of simple harmonic motion. Here we have covered relevant aspects of oscillation in the article. We learned the definition, parameters that govern the oscillation, expressions used for its calculation, and its different types: free, forced, and damped oscillation, along with examples.