# All Questions

6 views

### An amplifier with feedback

I have some problems with this circuitry. I should find Uout/Es, lower frequency limit, upper frequency limit and Re, when Uout=Up/2. Thank you for all possible information.
4 views

### Braking force required to allow bike to move down slope with an arbitrary constant velocity

Find the braking force required to allow a bike to move down a frictionless slope, inclined at $\theta$ radians above horizontal, with a constant velocity of v m/s. I'm confused because Newton's 2nd ...
12 views

### Why does a window layer is on top of the absorber layer in solar cells and not below it?

In solar cells there is a p-n junction. P-type semiconductor (for example CdTe) is often absorber layer because of its carrier lifetime and mobilities. In case of CdS/CdTe, CdS is n-type window layer ...
8 views

### What is quark transverse momentum?

When you google my question you get something on the order of 400 000 results but none of them explains how it is defined (No I didn't check them all). I know what the words quarks, transverse and ...
3 views

### In the context of non-resonant Raman spectroscopy, could a $CO_2$ molecule in a virtual state induce a dipole in an adjacent molecule?

When performing Raman spectroscopy (http://en.wikipedia.org/wiki/Raman_spectroscopy), one irradiates a chemical compound or material with light of some appropriate wavelength and looks for inelastic ...
7 views

### The effect of dark lines in the Sun's spectrum on reflected paint/ color

Its well known that the Sun's spectrum is not continuous, and that there are dark bands within the suns spectrum. Is it possible to produce a color of paint that is bright in, say, indoor lighting and ...
38 views

### Do electrons collapse into nucleus, if electrons in the atom are constantly excited?

From the Bohr's atomic model, it is clear that electron can have only certain definite energy levels. When the electron is present as close to the nucleus as possible, the atom has the minimum ...
33 views

### Number of blades in a helicopter rotor

I was wondering how it is possible to determine what is the optimal number of blades in a helicopter rotor. I think that the length of the blade is involved as a longer blades would have to spin ...
29 views

### Does coffee with cream cool slower than black coffee?

At Modernist Cuisine, Nathan Myhrvold states that "Coffee with cream cools about 20% slower than black coffee". He then gives three reasons, two of them related to radiation and the third one to the ...