DNA sculpture
http://seattlepi.nwsource.com/visualart/159686_architecture09.html
This is a double helix bridge that recalls the DNA structure in Seattle Washington. There are quite a few DNA or double helix structures.
Another possibility is the third form of carbon called Buckminster...
Practically, one way to deal with temperature and conductivity is through resistivity which is 1/sigma. Resistivity is fairly easy to measure. At room temperature, resistivity is proportional to temperature (rho =constant + A*T) The coefficient, A, is often tabulated and its temperature...
There is indeed no exact cut-off between semiconductor and an insulator. The numbers I gave should give a rough idea of the size of the energy gap in a semi-conductor compared to an insulator and there are always exceptions. "Solid State Physics" By Ashcroft and Mermin gives these values.
Recall that in a semiconductor, almost all of the electrons are in a full valence band. To conduct, electrons must jump a small energy gap (<2 eV) and then enter an unoccupied level in the next highest band. Your description about electrons jumping to a higher level in the conduction band is...
I apologize for being so long and using several replies, but I’ve had some trouble with my computer.
Now, a formula for reflectivity in the visible region. The reflectivity for metals is almost one:
R = 1 – a small number. (Generally .95)
An approximate formula is:
R = 1 – 2/(plasma...
This layman’s reasoning was carefully worded especially including the word ‘efficiency.’
The color of copper and gold are related to the lattice. When metal atoms form a solid crystal, the individual orbitals are thought to become bands because of the Pauli exclusion principle. The valence...
Going further, the efficiency of this process depends on the selection rules that apply to the atomic orbitals from which the energy band had formed. If the efficiency of absorption and reemission is approximately equal at all optical energies, then the different colors in white light will be...
Luster is the glow of reflected light and is not necessarily related to color although the discussion here is interesting.
In layman’s terms metals reflect almost all incident light regardless of wavelength in the visible range and are therefore essentially colorless. The relatively loose...
"The color in the transition metals (d-block) is predominantly due to the splitting of the d shell orbitals into slightly different energy levels. As a result, certain wavelengths of energy can be absorbed by the d-block elements (with electrons jumping between these slightly different energy...
The applets for the Bernoulli principle are neat, thanks for the links.
Ok, we can leave the Bernoulli principle out as a special aerodynamic effect.
I agree, if the bucket is falling with no air resistance, the water will not leak out of the bucket through the hole because they are both...
Inside the bucket, at the hole, there is no moving air, just water. I may have to look closer at the Bernoulli equation P2 - P1 = .5 (rho H20) v(h20)^2 0- .5(rho air)v(air)^2 more carefully though.
I've considered the terminal velocity a little more. The bucket is no longer in free fall...
Gravity acts vertically, so it cannot directly cause the leak from the side of the bucket. Indirectly it does through the pressure that the water above the hole exerts on the water at the hole. Pressure = density of water x height of water above the hole x a. a = acceleration of the water =...
Woops! Yep, you're right, I was thinking the hole was on the bottom of the bucket. I do think the water would flow out when the bucket reaches terminal velocity because the weight of the water above the hole forces the water out of the bucket through the hole.
I agree, I think Bernoulli's equation supports this idea too after the bucket reaches terminal velocity.
The equation for wind resistance assuming resistance is proporional to velocity squared is:
F = .5 c_d \rho v^2 A
The only parameter that might be different for the bucket and the...
Use a different form of Bragg's law
Hopefully, I won't mess up the Latex typsetting too much, I'll try to come back and fix it later.
a = .361 nm
Braggs law using the Reciprocal lattice vector G is
k = (1/2)G
Then the energy is
E = {hbar^2}{k^2}/(2m)
Ignore the first "/" in this...