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Resonance

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Resonance in physics is a phenomenon of amplifying the frequency of an object by an externally vibrating object when its frequencies match. Resonance can cause serious effects on the vibratory motion of any object. We have observed that a band of soldiers marching in a sink can sometimes cause a bridge to collapse. This is because of resonance motion.

In this article, we will learn about, Resonance Definition, Examples of Resonance in Physics, Resonant Frequency, and others in detail.

What is Resonance?

Resonance in Physics is defined as,

“A phenomenon in which an external force or a vibrating system forces another system around it to vibrate with greater amplitude at a specified frequency of operation.”

Resonance in Physics

In physics concept of Resonance is defined as,

If an external force or vibrating force forces another system to vibrate with greater amplitude at a specified frequency of operation is called Resonance.

When Does Resonance Occur?

Resonance is a natural phenomenon and occurs in various cases, the main cause of resonance is, the matching of frequencies of any object with the external object which increases the amplitude of the initial object.

Wave Resonance

Wave resonance occurs when a periodic force is applied to a system at or near its natural frequency, leading to the amplification of the oscillations of the system. This phenomenon occurs in various physical systems, including mechanical, electrical, and acoustic systems.

For example, think of pushing someone on a swing. If you push the swing at just the right moment and with the right frequency, you’ll notice that the motion of swing becomes much larger. This is because your pushes are resonating with the natural frequency of the swing, amplifying its motion.

Examples of Resonance

Resonance phenomenon is widely used in various examples and some of the most common examples of resonance observed by us in our daily life are,

Musical Instruments

The concept of resonance is widely used in tuning and designing musical instruments. Every musical instrument has a natural frequency of vibration these natural frequencies of the vibrations are called the harmonics of the instrument. If another object is allowed to move at the natural frequency of the musical instrument then its natural frequency increases exponentially and this phenomenon is called resonance.

Various musical instrument like Drums, Guitars, Piano, etc is tuned using this concept.

Resonance in RLC Circuits

In RLC circuit that is joint in series combination resonance occurs when the reactive effects of the inductor and capacitor cancel each other out, resulting in a purely resistive circuit. In this situation, the circuit exhibits some interesting properties, such as a maximum current and a minimum impedance.

Radio and Television

Old Radio and Television also work on the principle of resonance there is an antenna attached to this equipment that is made to vibrate at some specific frequency which allows us to amplify the frequency of the programs which we want to watch or listen to and then they are made to display these on the screen. For example, we have seen our grandparents using old radios and tuning them to get the desired frequency which then plays the songs this old radio uses the concept of resonance to play songs.

Bridge

Sometimes we have seen that some bridges suddenly collapsed by the strong wings or even by the parading soldiers even though they are made to withstand much greater forces. This happens when the vibrations created by the motion of marching soldiers, or the strong winds make the bridge vibrate at its natural frequency which results in the resonance and highly amplifying the small frequency of the soldiers marching or winds, resulting in the collapse of the bridge.

Shattering of Glass by an Opera Singer

An opera singer shatters the glass tumbler or other thing by making its pitch very high and adjusting it to match the natural frequency of the glass so it resonates making its amplitude rise exponentially and breaking the glass.

Swing

The motion of a swing resembles the motion of a pendulum and it can also be made to resonate which increases its natural frequency. Suppose if you play in a swing you go back and forth in the string and then the if you move with the natural frequency of the swing i.e. you are in sync with the swing then we say that you and the swing are in resonance in this situation we have to apply minimal force to maintain the motion of the swing and applying a little extra push take us to a higher height.

Resonant Frequency

Resonant Frequency is defined as the frequency at which the oscillation of an object is at maximum amplitude. The small forces near to the resonant frequency contribute to the large amplitude oscillation of the object.

How to Calculate Resonant Frequency?

Resonant frequency is the frequency of frequency that allows the object to vibrate at the highest amplitude. This occurs when an object is made to vibrate at its natural frequency increasing the amplitude exponentially. Resonating frequency is denoted by the symbol fo

The Resonant Frequency of an object can be calculated using the formula,

v = λfo

where,

  • v is Speed
  • λ is Wavelength
  • fo is Resonant Frequency

Different Types of Resonance

Resonance is of different types and the most common types of resonance observed are,

  • Mechanical Resonance
  • Acoustic Resonance
  • Electrical Resonance
  • Optical Resonance 

Mechanical Resonance

Mechanical Resonance is a phenomenon that occurs in a mechanical structure when it starts vibrating at a resonant frequency with maximum amplitude. This happens because the vibrating frequency of an external object matches the frequency of a mechanical structure.  For example, when a band of soldiers marches on a bridge, the frequency of the bridge matches the frequency of movement of the soldier thus making the bridge vibrate at a resonant frequency with maximum amplitude. Mechanical Resonance can lead to catastrophes such as the collapse of the structure. These are called Resonance Disasters.

The resonant frequency of a spring is calculated using the given formula:

fo = [1/2π × √(k/m)]

where,

  • m is Mass of Spring
  • k is Spring Constant

Acoustic Resonance

When the frequency of a musical instrument matches with the natural frequency of itself, then this phenomenon is referred to as Acoustic Resonance. It results in the amplification of sound waves originating from the instruments. Acoustic Resonance is an important factor in the making of musical instruments as it enables to design of the instruments in such as way that the sound produced is audible, especially in the case of a flute where a tube is used and all the musical instruments that use string to produce sound.

Electrical Resonance

Electrical Resonance is a phenomenon in which the magnitude of inductive and capacitive reactance are equal in magnitude. In the case of electrical resonance, the impedances of the circuit cancel out each other. The resonant frequency in an LC circuit is given by the formula

ω = 1/ √(LC)

ω = 2πf

where,

  • f is Frequency of Resonance
  • L is Inductance
  • C is Capacitance

Optical Resonance 

The phenomena of Optical Resonance can be achieved using an Optical Resonator. An Optical is a component of a laser and has two mirrors among which one is highly reflective and the other is partially reflective. Optical Resonator works as say for example we have a partially transparent mirror then the light is fed from outside to the resonator. We can achieve maximum transmission when the light entering the partial mirror matches its frequency with a resonator mode. This enhancement of frequency occurs in resonator intracavity. 

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Resonance Frequently Asked Questions

What is Resonance?

Resonance is phenomena of vibrating an object at larger amplitude when its frequency matches with an externally vibrating object.

What are Types of Resonance?

Different types of Resonance are,

  • Mechanical Resonance
  • Acoustic Resonance
  • Optical Resonance

What are Examples of Resonance?

Oscillations in pendulum, in swings, sound produced in musical instruments, etc. are various examples of resonance.

What causes Resonance to Occur?

When the frequency of an object matches the frequency of an externally vibrating object then Resonance occurs.

What is Resonant Frequency?

The frequency at which an object vibrates with the highest amplitude is called its Resonant Frequency.

What is Resonance Meaning

Resonance is defined as the phenomenon where, the frequency of vibration of an object matches the frequency of vibration of an external object this results in the amplification of the amplitude of object.

What is Mechanical Resonance?

Mechanical Resonance refers to a mechanical system’s tendency to respond with greater amplitude when the frequency of its oscillations is the same as the system’s natural frequency of vibration.



Last Updated : 06 Mar, 2024
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