I'm trying to understand electromagnetic wave resonance a little better and am stuck. Specifically I'm unclear of the amount of energy required in the applied wave to excite to resonance. For example, if observing a given wave (wave 1) of a known and fixed frequency AND polarity on an oscilloscope at a known and fixed amplitude (say 10 units), what amplitude of an applied wave (wave 2) will excite both to resonance? That's assuming of course wave 2 is of the same frequency, polarity, and phase. Can resonance occur when the amplitude of the applied wave 2 is less than wave 1? Or does wave 2 need an amplitude equal to wave 1 for it to occur? Or perhaps wave 2 even needs a larger amplitude than wave 1 for resonance to occur? This I don't understand. Also, what duration of wave (cycles) can resonance occur in? Can resonance still occur in just a single peak to peak cycle? Thanks in advance for enlighting me ;^).
resonance.... um your post confussed me... so I will say this... resonate action... is likenned to the natural vibratory state of any given system... in an electrical system... using an LC CURCUIT.... where we have our signal generator... connected to an inductor and capacitor connected in series.... there is a point where the reactive resistance to the energy flow is least... that frequency.. would be the resonate frequency of that LC system. i.e.. any lc system... has specific resistances.. in the wire of the coil.... at frequencies lower than resonate... the coil exibites more resistance.. called reactance... and above the resonate frequency, we also have reactance. but at resonace we only have the physical resistance of the wire... only. this is how.. we can use a coil and capacitor to tune in radio signals.. cause only the resonate frequency can easily pass threw... all other frequencies are met with reactive resistance.... reducing the energy flow by alot. there is also such a thing as resonate rise... i.e.. if you had a coil... and both ends of it were connected to a capacitor... and it was energized by another coil, forming a transformer... then if the pulses from the pushing primary coil... was at the resonate frequency of the secondary coil and capacity system, then the energy applied by the primary coil can actually collect and build up in the secondary coil... i.e.. with each wave of energy from the primary... the energy feeds and develops in the secondary... then as the next wave comes in... it simply adds its energy to the energy wave which was formed in the secondary, and as long as they are in tune and at resnonace then the wave of energy in the secondary will build up... this is called resonate rise... and is the basis of the operation of a tesla coil, which then allows us to... with resonance... to generate voltages of almost any potential. resonance is very powerful. -MT
There must be some interaction in the system for resonance to occur - i.e. an energy transfer from one part of the system to another. Two waves on their own just undergo superposition, regardless of amplitude, frequency or whatever. There is no resonance. A good example of resonance is where a mass on a spring is driven by an external source at the same frequency as the "natural" frequency of the system. Then, it doesn't matter how small the driving force is. The oscillations will build until the spring breaks.
Hi Squinky, welcome to SciForums. Amazingly, MT is right. Even more amazingly, he agrees with JamesR and me. Resonance is a property of systems, not waves. It is a frequency at which the system is efficient at transfering energy with little or no loss. -Dale
i assume you are talking about radio waves. resonance is a property of LC 'tank' circuits the amount of energy required from the exciting waveform is vanishingly small in a well made circuit also to my knowledge resonance in tank circuits is sine wave in nature
Sorry for not being clearer. I did indeed mean sinewaves in a LC circuit (but also optical resonance too). And I should have stated that observed wave 1 was the natural frequency and that observed wave 2 was the oscillatory one and they were interacting. But your replies have helped me and I get it now. Googling "resonate rise" supplied me the answer I was looking for...and that is it takes decreasing amounts of energy at the right frequency and phase to maintain resonance. Understanding this immeadiately made me think of a child on a swing. To maintain a plus/minus 30 degree arc from vertical requires less and less energy from the child. Guess I'm so old now I forgot this ;^). Thank you gentlemen.
there is no better book on the subject then... TESLAS BOOK.. 'EXPERIMENTS with ALTERNATE CURRENT of high potential and high frequency' a lecture delivered before the institute of electrical engineers, london. may 20, 1891 it is in my opinion... the most inspiration work on electronic engineering ever writen... its like poetry... but its hard engineering.. if you love science, and electronics and want to be really educated on the subject. it is the first book, and the last... to start with. i have a copy in front of me.. now.. as i write this. it is for me... a treasure. AND UNLESS ANOTHER COPY WAS AVAILBLE FOR ME TO BUY... i wouldnt sell it. luckily... im sure it is still be in print. -MT
