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2

Of course. This is how antennas work. The Maxwell equations make this possible. The metal as a conductor has electrons in what is called the conduction band, and these are free from the ions in the metal lattice. The oscillating electric field $\vec E$ or $\vec D = \epsilon \vec E$ given by $$ \nabla\times {\vec H} = \frac{4\pi}{c} {\vec J} - ...


1

This is actually much more subtle, the question is very deep and whole books are written about theory of coherence in optics, quantum mechanics etc. What is important is that you might have an ensemble of sources (say in a lightbulb) which all emit light of the same frequencies but in random moments, making the relative phases between different light pulses ...


0

Yes. Omega is the time derivative of phi. Phi1 dot = phi2 dot means omegas are the same. See my other answer a couple days ago on the subtleties of coherency. There is phase noise on any transmitter and freq as a result has drift and random noise. It depends on the time proof, it could be coherent to 1 part in 10^6 for milliseconds and 1 in 10^5 for a sec. ...


-1

The speed of sound depends on the medium in which it travels. In air it can be affected by ambient temp, relative humidity , as well as atmospheric pressure. The speed usual quoted at a standard temp and pressure. http://byjus.com/physics/speed-of-sound-propagation/


0

And actually at infinite Hertz, the air will not vibrate, so we'll hear nothing. And even if it does, our hearing ability is only till 20kHz. It'll be like passing direct current through a speaker, the membrane is vibrating, but unfortunately we hear nothing!


28

You're correct and the video is mistaken. In fact, if cesium atoms were constantly oscillating between the two hyperfine states, cesium beam clocks wouldn't work at all! In its simplest form, a cesium beam clock uses a magnet to separate a stream of atoms into two streams based on their hyperfine state; one state is selected to continue down the tube to be ...


0

Tpg2114 is right. It's the sonic boom. All the wavefronts in front of the airplane bunch up and add up, and you hear a thump. It travels with the aircraft. To go past it is like going through a barrier because of the high pressure there. Once you pass it the sonic boom trails behind the aircraft. See it at ...


2

There is no such thing as "infinite hertz". The equation to calculate the doppler shifted frequency breaks down when the emitter travels at, or faster than, the speed of sound. What actually happens when an object travels that fast is the sound waves all pile together and form a shock wave. This is what creates the sonic boom.


8

Yes, they really are oscillating between two different states (not simply driven in one direction), but as you suspect they are not oscillating at the reference frequency. Rather than "just" sending radiation at the atoms to absorb, they also interact with an oscillating magnetic field (which is at the reference frequency). This field spurs some of the ...


32

The definition for the cesium clock is: 9192631770 cycles per second is frequency of the radio waves which cause maximum resonance, a physically measurable condition, in the cesium atoms. This corresponds to a particular tuning of the radio. Keeping it tuned provides the reference frequency cited.


5

Concerning the meaning of "temperature coefficient of [measurement]". Generally, when it appears without additional adjectives, the "temperature coefficient" of anything refers to the fractional slope of a linear fit to that quantity as a function of temperature. In the introductory class we often introduce A linear coefficient of thermal expansion, in ...


2

$T= k f^2$ and $T + \Delta T= k(f + \Delta f)^2 \Rightarrow 1 + \frac{\Delta T}{T} = (1+ \frac{\Delta f}{f})^2 = 1+ \frac {2 \Delta f}{f} + \left ( \frac{\Delta f}{f}\right )^2$ $$\frac{\Delta T}{T} = \frac {2 \Delta f}{f} + \left ( \frac{\Delta f}{f}\right )^2$$ So your methods differ by the last term


1

when a signal is analyzed in time domain they are called spectrum or you can say that signal is in spectral domain. but when the signal is analyzed in frequency domain and amplitude of such signal is taken to analyzed the signal then they are said to be in cepstral domain.


3

The equation for the period $T$ comes by using Newton's second law $F=ma$ to obtain the equation of motion of the spring-mass system $$-kx =ma \Rightarrow a=-\frac k m$$ where $x$ is the displacement from a fixed point and $a$ is the acceleration. This equation is of the form $a=-\omega^2 x$ where $\omega$ is a constant of the simple harmonic motion. It ...


6

In this equation $\omega$ does not refer to the speed of angular motion, but the frequency of oscillation when measured in angular terms (usually radians/sec, but it can be degrees/sec). Frequency is usually measured in cycles per second (Hertz), but it is sometimes more conveniently measured in angular terms, when it is called angular frequency. The angle ...


5

Imagine a point $P$ moving on a circle of radius $R$ with angular velocity $\omega$. The projection of $P$ onto the $y$-axis is: $$y=R\sin \theta=R\sin \omega t$$ The point $P'$ is in simple harmonic oscillation (SHO). For the spring mass system it just so happens that: $$x=A\sin \omega t$$ where: $$\omega=\sqrt{\frac{k}{m}}$$ So although there is no ...


2

This question raises several concerns. From a purely signal processing point-of-view, where the aforementioned pulse is not a photon, but rather a time-domain pulse of a certain duration (here less than 10^-100 seconds)--then NO: you cannot have pulses shorter than the period of wave in question--as the wave an be defined. Consider sound: when a 440Hz A note ...


0

The discussion which has ensued from the question here and in A conceptual doubt regarding forced oscillations and resonance hinges on how resonance is defined for particular situations and what is meant by the natural frequency of the driven system. An often used definition of resonance is: Resonance is the maximum steady state response of a driven ...


2

Yes, it is possible to have two different waves of different frequencies on a string (Imagine driving the string with a square wave; it consists of multiple frequencies with multiple amplitudes; See Fourier transform). However, the velocity of waves on a thin string are constant and depend only on the tension of the string and the density. Thus, you cannot ...


2

You should remember one thing : electromagnetic field is just a spatial representation of how electric charges interact with each other, and by "interact" I actually mean "exchange some energy". Electrostatic and magnetostatic energies Lets imagine that we want to build "from scratch" a given charge distribution $\rho(\textbf{x})$. That means that we ...


4

Data is taken at different frequencies because different frequencies contain different information. The data here covers a factor of 9 in frequency (equivalently wavelength). Compare this to the factor of 2 accessible by human vision. Given two objects that have the same power at one end of the frequency range, they could very well differ at the other end. ...


-3

EM Waves are basically spinnings of photons. To create a EM Wave, you basically move some electrons in a directional way(think of an antenna). Electron is a charged particle as well as protons. Charged particles emit photons, and if you emit photons in an ordered way such as this: You are seeing a dipol antenna. When you apply negative voltage(intense ...


-2

The energy is carried in individual photons. A photon with twice the frequency has twice the energy. x-rays are made of photons with higher frequencies. The energy is transferred as kinetic energy as with the photoelectric effect. The energy of a photon is calculated as E=hf (Energy=Plank's constant x the frequency).


1

I'm assuming that you are asking this question in context of an L-C circuit. The reasonant frequency of an L-C circuit is given by the formula $$f = \frac{1}{2\pi}\sqrt{\frac{L}{C}}$$ where L is the inductance of the inductor and C is the capacitance of the capacitor. Hence if any of these two values are changed the reasonant frequency of the circuit will ...


0

Phase means the stage in its cycle which a wave has reached. Peak and trough are phases of the cycle, but it is more useful mathematically to describe phase in radians, as though the wave is a point moving round a circular track - the phase is the angle which the current radius makes with the starting radius.


1

Phase is the argument of the wave. This is the definition written in my book and quite hard for beginners (like me). So the question "What is phase?" Phase is the quantity which tells us the status of the wave. In normal x-y grid like x-axis tells us the distance from the origin, in similar way you can think a phase is along x-axis and it gives ...


3

The clue here is " how far apart". The question is asking for distance which must be in terms of the wave's wavelength. Phase measures fractions of wavelength. And you are given information of the wave's speed and the periodic time in which it propagates (frequency). The fundamental "distance = rate * time" applies in terms of the wave speed, wavelength and ...


0

Well, since this question is very well covered in literature, I will provide the first steps and you can do the discussion by yourself. Usually, the first approximation is planar wave in a duct of varying cross section area $S = S(x)$. The modified wave equation for such a case is called the Webster equation: $$ \frac{\partial^2 p}{\partial x^2} + ...


0

From the library of expert witnesses: The fundamental theory for voice identification rests on the premise that every voice is individually characteristic enough to distinguish it from others through voiceprint analysis. There are two general factors involved in the process of human speech. The first factor in determining voice uniqueness lies in the ...



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