Tag Info

New answers tagged

1

The Wien displacement law gives the maximum of a function, so the way to compute it is to start with the Planck function in frequency domain, $$ B(\nu,T)=\frac{8\pi\nu^2}{c^3}\frac{h\nu}{e^{h\nu/kT}-1} $$ Take the derivative with respect to $\nu$, set it equal to zero and solve for $\nu$. You'll likely have to use some numerical methods (e.g., iterative ...


2

Here are some topics to read about: Frequency doubling, also called second-harmonic generation as Johannes mentions. Here, you put one wave into a medium, and some fraction of it is converted to a wave with a different frequency. By carefully engineering the medium you can get quite a high conversion percentage. Other nonlinear optical processes, not just ...


1

Although normally considered as photon interactions, any inelastic scattering process will result in the alteration of the frequency of the electromagnetic radiation. An obvious example is Compton scattering, where high energy (X-rays+) light scatters from free electrons. The scattered light has lower energy and longer wavelengths than the light incident ...


2

To understand it in the easiest way either look at it as frequency... What you are describing is the frequency $f$. The frequency is an amount of turns or revolutions or periods or something else that happen every second. Your frequency here is $n$ turns per second. Then you have this formula to find angular frequency: $\omega=2 \pi f$ Or as a number of ...


3

The speed of sound is given by the Newton-Laplace equation: $$ v = \sqrt{\frac{K}{\rho}} $$ where $K$ is the bulk modulus (i.e. a measure of stiffness) and $\rho$ is the density. The physical interpretation of this is fairly obvious. Stiffer substances recoil faster from a displacement so increasing the stiffness increases the speed of sound. Heavier ...


-1

The speed of sound depends on the average speed the molecules are moving. Increasing temperature means increasing the average velocity of the gas molecules, hence increasing the speed of sound. And vice versa. Wavelength is related to the speed of sound and frequency


0

Update: After simulating a little more, it seems that Drew Noel had the right hunch after all: by inserting a 100pF capacitor in parallel to the 110 Ohm and 11kOhm resistors, we can shift the resonance frequencies up from 11.25kHz to 12.11kHz, which gets us into the right ballpark. 150pF will give 12.71kHz for the upper frequency and 200pF will result in ...


1

Here is a slightly different take on this using the boundary conditions for electromagnetic fields at an interface. A key boundary condition, that is derived from Faraday's law, is that the component of the E-field tangential to the boundary must be continuous. So take an EM wave travelling at normal incidence with the electric field solely in a direction ...


0

OK, I get your answer, but as this is a homework question and you have really not shown any attempt to get the solution I cannot show you it. The doppler equation you have is fine: I would write it as $\omega = \omega_{\rm star} \gamma (1-v)$ where we are using units with $c=1$. You then need to use a standard relationship between acceleration in the two ...


0

A number of factors influence the sound of a wind chime: The length of the pipe The diameter of the pipe The thickness of the pipe The material of the pipe (density, young's modulus) How the pipe is struck How the pipe is suspended These last two points are really important - when you strike exactly in the middle, you will excite the odd modes (only) of ...


1

I sure hope my assumption is correct that you're just needing help understanding where an equation that you encountered in your book came from, rather than this having been a homework problem that you were supposed to do. I fully support the policy here of not doing people's homework problems for them. From the starting point of ...


0

See the standard text by Peter J. Brockwell & Richard A. Davis "Time Series:Theory and Methods" 2 ed, p.331, where authors define $\omega_j=2\pi j/n\in(-\pi,\pi]$ (integer multiples of the fundamental frequency $2\pi /n$) as Fourier frequencies. Later on p.335, they say "if $\omega$ is not a Fourier frequency, the analysis is a little more ...



Top 50 recent answers are included