Question

what is resonance produced in objects? what are the basic criteria? how can we make something to resonate?

Answer 1

I got this definition from a certain site hope it helps

Answer 2

It is the dramatic increase in amplitude of a periodic system that occurs when the driving frequency applied is equal to the natural frequency of the system.....

Answer 3

every material in this universe is made up of some basic geometry. based on that structural geometry, based on the degrees of freedom, the material has a natural frequency of oscillation.
This means that if this material is acted upon by a driving force that oscillates with this natural frequency, the target material starts osciallating with an increased amplitude. This is called resonance.

Answer 4

nice but what are the ways to induce resonance?

Answer 5

it depends on the target system.
a simple air column in a tube resonates by induced vibrations in the air.
a tuning fork resonates in the vicinity of another tuning fork. again air being the culprit to transfer the inducing vibrations.

on the other hand, look at the celestial bodies. the moons of jupiter- Ganemede, Europa and Io, they have resoanant orbital motions w.r.t each other. their time periods are in ratio 1:2:4. Here the gravitatinal force itself conspired to induce resonance.

There is always some driving force to cause resonance.

Answer 6

Resonance is the optimisation of energy transfer between a driving system and a receiving one.

What kausarsalley quoted is correct: you need equality of frequencies.
In the case of wave transfer, this can also be seen as the adaptation of the impedance of the medium in which the incident wave is travelling and that of the transmitted wave.

If impedances are too different from one another, the energy of the incident wave will not be transmitted but will be reflected in the first medium.

Answer 7

Mechanical resonance can easiy be appreciated. Most real rigid bodies are eleastic to some extent. And as such can be set into a vibration or oscillation by striking it or interacting with it with some other type of force. This vibration is charactistic of the shape and material of the object. When you apply a force to an object and you distort it even ever so slightly you do work and transfer energy to the body. the body being elsastic will rebound and vibrate some more but real bodies have a characteristics like an internal friction which causes the vibration to dissapate with time usually quickly. If you apply the force before the vibration dissapates the vibration can be sustained. If the force applied is in tune with the characteris frequency of the bodies vibration the vibration will increase in intensity and the body will accumulate more energy before it can be dissapated. The build up in energy can continue until the vibration distorts the object to the extent that it exceeds the elastic limit of the material of the object. An example is a singer holding a tone equal to the characteristic frequency of a wine glass to cause it to eventually break. The "singing" of stretched cable in a high wind is another example of resonance. The body of a guitar or other string instrument. An annoying rattle in a car at a certain speed.
There are analogies in other areas of physics as in AC circuit theory. All we need is a periodically varying force applied to a body or structure equal to that structure characteristic vibration and long enough for energy to accumulate and in mechanical systems to cause visual movement sometimes with destructive affect.

Google the" Tacoma Narrows Bridge" for a famous example.

Answer 8

take a glass of wine, a good one which is very thin.
Give it a small hit and listen.
Can you make the glass play without touching it?
Yes you can, sing the same note with your mouth close to the glass for 3-5 sec, now listen
the glass vibrates and makes sound.
It will only happen if you sing the same note. the force of the air vibrations from your singing is very weak, but matching frequencies with the glass, you give it more and more energy with every vibration,
Just like when pushing a child on a seesaw, you push at the right time ye?
thats resonance. applying a force at a specific frequency which the natural frequency of the movment of the object.

a nice video by vihart
http://www.youtube.com/watch?v=i_0DXxNeaQ0

You can make a string play its note y singing the same note thats resonance

you can build an elctric circuit that produces ac at a frequnecy of your choice, Lets say
ac at frequencies between 88-105 MHz

now connect to an antena, tune your circut to a certain frequency, and the circuit will start producing current from the weak signal that the antena is getting

What about molecules? most of them can vibrate
Thats the idea of a microwave!

A trumept...
well the tube holds air. if you just strike a tube 0f about 20-40cm at one end you will a funny note.
Now place your mouth at the end and make a "farting" noise of the same note...
Thats how you play the Trumpet, and thats resonance.
Having an object (the tube of air) that vibrate at a specific frequency and bringing it to a big amlitude by applying a force with the same frequency (the farting note with the lips)!

see through trombone mouthpiece playing
https://www.youtube.com/watch?v=n92c3-nrSDM
https://www.youtube.com/watch?v=gmBDG_wAeS4

breaking glass with sound
https://www.youtube.com/watch?v=ruqjAoB0vNQ

mythbusters have a good one about this

and ofcourse the amazing paul Hewitt with his one minute videos
https://www.youtube.com/watch?v=zWKiWaiM3Pw

Answer 9

can I get some formulae for this?

Answer 10

Yes,
The equation of the form \[a \frac{ d ^{2} x}{ dt ^{2} }+b \frac{ dx }{dt}+cx=Xcos(wt) \]is the generic equation for harmonic motion. where a is an inertia factor, b is a damping(energy dissipating ) factor , c is a (energy) restoring factor and X is a driving(energy enhancing) force factor. The solution of this diff eq. is\[x=\frac{ X }{\sqrt{\left( c-a \omega ^{2} \right)^{2}+b ^{2}\omega ^{2}}}\cos \left( \omega t-\arctan \left( \frac{ b \omega }{ \left( c-a \omega ^{2} \right) } \right) \right)\]
Note the denominator has a maximum at \[c=a \omega ^{2}\] where omega is the 2 pi *resonance frequency. the frequency of max amplitude for x the max energy of the system.
Note the characteristic of the resonance curve a maximum in the plot of amplitude of the system vs frequency where the maximum amount of energy is stored at the resonant frequency.
If this maximum energy is beyond the capability of the object resonating, the object will be destroyed. A breaking wine glass a undulating bridge(Tacoma Narrows Bridge)
If the object can handle the energy it is storing the vibration or oscillation will be the greatest.