Could anybody explain Scalar- and ELF-waves??
968111
Please re-submit your question explaining what medium the waves propagate in.\nDoes ELF refer to Extra Low Frequency radio waves in your question?
437661
This requires the use of doppler shift formula for a moving source and stationary observer:\n\nf = f0 ( v / ( v + u ) )\n\nf0 = actual frequency = 5\nv = speed of wave = 20\nu = relative velocity of source away from observer = -10\n(since travelling toward)\n\nf = observed frequency = 10 Hz\n\nNow velocity = v = fl = frequency * wavelength\n\nso wavlength l = v / f = 20 / 10 = 2m
463641
see\nhttp://hyperphysics.phy-astr.gsu.edu/hbase/surten2.html#c1\n\n here you can find the answer for your question with MATHEMATICAL EXPLANATIONS.
317881
Such a pulse produces a standing wave. In such standing wave energy is not transferred from one place to another.\n\nAt each instant we see a wave, but the waves do not move.\n\nThere are certain points which never move, they are called nodes.\n\nBut between nodes the points are displaced.\n\nAt one instant, all points are motion less.\n\nAfter this instant, points that previously went up will now come down and vice versa.\n\nExcept the nodal points, all points are oscillating between potential and kinetic energy. \n\nThe maximum displacement corresponds to potential energy and the mean position corresponds to kinetic energy.\n\nAt the instant when all points are motion less, ALL POINTS EXCEPT THE NODAL POINTS have kinetic energy, by which they continue their oscillation.
745636
The main concept to understand is that of a carrier wave.  The radio wave is that.  A radio wave is electro-magnetic radiation, which, unlike other waves, is not a vibration within a medium, like sound waves for example, which are the propagation of alternating high and low pressure within the air, or other fluid media.  Electro-magnetic waves are a self propagating electro-magnetic effect which can travel even in a vacuum.  Electro-magnetic radiation is a pulsing stream of energy where the pulses are at a constant frequency.  What we perceive as different phenomenon are in fact the same electromagnetic radiation but at different frequencies.  Microwaves, Radio, Ultra-violet, Visible Light, and Infra-red, are all electro-magnetic radiation moving down the scale from high to low frequency.\n\nThe radio transmitter sends out radio waves at a specific frequency or band of frequencies.  The aerial of the receiver develops tiny electric currents in it as the radio wave flows past it.  These are pulsing currents at the same frequency as the radio wave, but these pulses are not in themselves the content of speech or music.  This content, or signal, is carried in the wave, hence the concept of the carrier wave.\n\nIt is easier to understand Amplitude Modulation or AM radio so I will restrict myself to that.  If you imagine a radio wave as a very long string with the pulses like beads on it, all spaced at precise intervals, then imagine that the beads slowly getter bigger and smaller along its length.  Each bead is a packet of energy in the wave and all occur at the same frequency, but where the beads get bigger there is more energy in the packet.  It only takes a little more imagination now to see how the pattern of a sound wave can be represented by the bulging out of the beads, and their getting smaller.  This is called the amplitude.\n\nLooking at it in practical terms, at the transmitter end sound is converted in the microphone into a corresponding pattern of changes in the current flowing through the microphone.  That is your signal.  That signal which is at a low electrical power, is used to create the same pattern but in a circuit of much higher electrical power - that is what an amplifier does.  The device used to transfer the pattern is called a transistor, which uses the low powered circuit to control the flow in the high powered circuit.\n\nThe amplified signal is fed to the transmitter aerial, so now that pattern of electrical energy, identical to the pattern of the sound picked up by the microphone, comes out of the aerial as radio waves, with the pattern held in the varying amplitude of the radio wave.\n\nNow comes a trick to follow.  If there are thousands of transmitters all radiating radio waves all over the place, how come your radio only picks up the one signal.  This is where the tuner comes in.  The principle of radio tuning depends on the opposite properties of coils and capacitors.  I don't know if you know what these are, but it doesn't matter if you don't.  Both of these devices have a special kind of resistance to electricity known as impedance.  Impedance only operates where the current is varying.  The voltages and currents in our radio Ariel will be varying at exactly the same frequency as each radio wave it is exposed to, so if we pass that current through either a coil or a capacitor there will be an impedance in the circuit.  Now the impedance of the coil increases as the frequency gets higher and the impedance of the capacitor gets higher as the frequency gets lower.  An AM tuning circuit simply passes the signal current through both a coil and a capacitor at the same time, and the capacitor is a mechanically variable one, so by turning a knob you can increase or decrease the capacitance.  The trick here is that as the capacitance changes the circuit will show least impedance to a specific frequency compared with all the others, so provided the frequencies are not too close, as the law requ
476327
"S-waves" are shear waves, wheras "P-waves" are sort of push-waves (essentially).  So because fluids are umm... fluids, you can't shear them.  Shearing is when you deform something by applying unequal stresses from three dimensions.  With a fluid, such a stress would make no difference, because fluids cannot be deformed, they meerly move.  This is why an S-wave that hits a fluid will only be propigated as a P-wave!  Weee!
769374
This sounds like it came out of a textbook. What is the name of the various propagation models?
131583
i would think that the radiation from the freqs listed above should all cause excite the water molecules in the same way but to differing extents. that's a very good question; i think i'll research it.
1118486
Suppose a charged particle moves at a more or less constant velocity v1 followed by a finite time interval t of acceleration resulting in a new velocity v2. The radiation emitted always spans a large range of frequencies which (as a rough approximation) goes from frequencies of about 0 to 1/t, dropping to zero at frequencies much higher than 1/t.\n\nFor the acceleration events in your examples: For an electron passing through a sharp local magetic field, t ~ a/v where a is the size of the region with the magnetic field and v the electron velocity. For a collision with a nucleus or other charged particle t ~ b/v where b is the impact parameter (the closest distance between the straight line trajectory of the electron and the particle it's colliding with).\n\nFor purposes of order of magnitude calculations, the total energy per frequency interval radiated by a particle with charge e (in gaussian cgs units) is roughly:\n\nd Energy/d omega  ~ e^2 * |v2-v1|^2/c^3\n\nfor frequencies in the region 0 < omega < 1/t.\n\nThere is never one single frequency emitted except when there's a sustained pure sinusoidal varying current as in a radio antenna. Of course atomic and nuclear transitions produce photons with precise frequencies (wavelengths) but those are not really the result of accelerating charges in the usual sense.
1000927
maybe this will help you.\n\nhttp://www.scarborough.k12.me.us/wis/teachers/dtewhey/webquest/nature/seismic_waves.htm
968675
A question I have wondered myself.\n\nThe best I can manage is this...\n\nI know that it is a thought experiment but it is actually impossible for the waves to be perfectly recombined as you suggest.\n\nFor example, if one of them passes through a partially reflective surface with the other undergoing its phase shift and then being sent back to reflect from the surface into the path then some of this energy will be transmitted through the partial reflector while some of the original ray will reflect off it.  These will then interfere constructively (there will be an additional phase shift).\n\nI think that there will always be this kind of loop-hole, no matter how you do it.\n\nIf you only do it approximately, so that the waves are very close to converging (with a phase shift) then you get an interference pattern that is pretty much zero along the central path (ie the first order solution is destructive to zero as expected) but with constructive interference elsewhere so that energy is conserved overall.\n\nI hope this is clear!
473172
You've actually got several concepts and questions merged together.\n\nWhen you ask "how does the aerial setup the waves from only the ac signal?"  I assume you're asking how any DC components of the signal get filtered out?\n\nA transverse electromagnetic wave involves both a VARYING electric field and a VARYING magnetic field, appearing at right angles to each other and to the direction of travel of the wave.\n\nAny DC component has no varying component, therefore, no wave is generated.  Although DC flowing through a wire creates electric and magnetic fields, no wave is generated because there is no variance in the fields.  \n\nThere are other electronics concepts that require the changing electromagnetic fields of AC to work.  A transformer uses AC, not DC.  A capacitor will block DC signals, but allow AC signals to pass.\n\nAlso, as you indicated, an efficient antenna has a matched impedance to the signal source in order to maximize the amount of engergy propagated by the antenna in the desired direction(s).
398594
You may be talkig about a square, sine, and sawtooth (triangle) waveforms. They look like their names imply on an oscilloscope. They have no special significance other than they are descriptive of the type of AC wave they describe. It is like asking what are the different colors and what are their significance?
812174
I don't quite understand your notation, but here is how I would do this:\nThe general equation is y(x,t) = A sin 2 pi (t/T - x/L), where\nA = amplitude = 0.12 m\nL = wavelength = 0.3 m\nT = period\nThe latter is not given, but you can get it from the wavespeed v, via the formula v=L/T. Hence T = L/V = 0.3/6.4 = 0.0469 s.\nPlug A, L and T in the general equation and compare the result to the expression given in the problem.\nLooking at your expression, I would guess \na = A = 0.12 m \nb = 1/T = 21.3 s^-1\nc = 1/L = 3.33  m^-1
253932
Electromagnetic radiation is a propagating wave in space with electric and magnetic components. These components oscillate at right angles to each other and to the direction of propagation.\n\nThe term electromagnetic radiation is also used as a synonym for electromagnetic waves in general, even if they are not radiating or travelling in free space. This sense includes, for example, light travelling through an optical fiber, or electrical energy travelling within a coaxial cable.\n\nElectromagnetic (EM) radiation carries energy and momentum which may be imparted when it interacts with matter.
164646
You mean a 'frequency of 5.10^12Hz'\n\nCan you work it out yourself?:\n\nRemember that the speed (v) of the wave is 3×10^8 m/s,\nand that the wavelength is given by v/f\n\n[Edit: Darn, Kirchwey - don't do Glow's homework for her! ;-) ]
631372
Wavelength (M/C) = Velocity (M/S) / Frequency (C/S)\n\nAmplitude addition/subtraction has to do w/ the relative starting phase/angle of the components & their harmonic relationship.  If they are the same freq w/ the same amplitude in phase the resultant wave has twice the amplitude (+).  However, the same to wave shifted 180degrees apart will result in a flat line (-). \n\nThe following is the formula for complex square wave.  Each component represents a harmonic @ the relative frequency & amplitude compared to the fundamental frequency [Asin(x)]:\n\nSin(x) + 1/3[sin(3X)] + 1/5[sin(5x)]... + 1/n[sin(nx)]\n\nHere the +/- symbols represent relative starting phase.  They are all initially in phase. The rational coeffiecent represents the relative amplitude & the nx represents the relative frequency.