Feb 2021

Different Types of Oscillations: Free, Damped, and Forced

February 18, 2021

What does a guitar, swing, or a rocking chair have in common? They all oscillate – in a way, they move back and forth between two points.

Oscillations can create waves. For example, a guitar produces sound waves, and the motion of slapping water with your hand can make water waves. Some waves are visible (e.g. visible light waves), while some are not (e.g. sound waves).

In physics, oscillation is the repeated variation of any quantity or measure in position or magnitude about a central point. The unit used for the number of oscillations per second is the Hertz. It is quantified using parameters such as frequency, amplitude, and time period. 

Properties of oscillation

  • The frequency (F) is defined as the number of complete oscillations per unit time.
  • The amplitude (A) is defined as the maximum displacement of an oscillator from its equilibrium position.
  • The time period (T) is defined as the time taken for one complete oscillation, in seconds. The relationship between frequency and period is f = 1/T

Simple harmonic motion

Simple harmonic motion is a very common type of periodic motion. It is used to model many systems where a mass oscillates about an equilibrium point, such as a mass on a spring, or a pendulum. In this oscillatory motion, the restoring force acts in the direction opposite to that of displacement of the object and is proportional to it. Any simple harmonic motion can be classified under three types of oscillation.

Different types of oscillation

There are 3 main types of Oscillation – Free, damped, and forced oscillation.

Free oscillation

When a body vibrates with its own frequency, it is called a free oscillation. The free oscillation has a constant amplitude and period without any external force to set the oscillation. An example would be the vibrations in a tuning fork.

Damped oscillation

Most free oscillations eventually die out due to the ever-present damping forces in our surrounding. The oscillation that decreases with time is called damped oscillation. Due to external factors such as friction or air resistance that results in damping, the amplitude of oscillation reduces with time, and this will result in energy loss from the system. An example would be the decaying oscillations of a pendulum.

Forced oscillation

When something oscillated by being influenced by an external periodic force, it is called a forced oscillation. Here, the amplitude of oscillation experiences damping but remains constant due to the other external energy supplied to it. For example, when you play with a toy that involves an object being supported by an elastic band suspended on your finger. In the beginning, if you hold your finger still, the object bounces up and down with a small amount of damping. If you move your finger up and down, the object will follow along. The object responds by oscillating with the increasing amplitude as you increase the frequency at which you move your fingers.

The phenomenon of driving a system with a frequency equal to its natural frequency is called resonance. The less damping a system has, the higher the amplitude of the forced oscillations near resonance. The more damping there is, the broader reaction it has to various driving frequencies.


Many things in our daily lives are associated with oscillations. If you are interested in learning more about waves and oscillations, Best Physics Tuition can help you out! We have A level and O level physics tuition that can get you prepped and going for the next test.

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