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1. A Change of ε with pressure for Semiconductors

In "Sado Adachi" book "Properties of Group-IV, III–V and II–VI Semiconductors" page 222, he reported that "both εs and ε∞ decrease almost linearly with increasing pressure", however i was not able to find any empirical formula to describe these relationship for materials InAs, InP, InSb, where...
2. Revisiting Newton's Second Law

I wonder why newton second law, define force as mass x acceleration, acceleration is the second time derivative of displacement, why he didn't define the force as mass x higher order time derivatives of displacement
3. I From Non Hermitian to Hermitian Matrix

Is there any way that i can convert a non-hermitian matrix to a hermitian matrix ?
4. I Spiral Equation

I am looking for a family of curves where if we consider one curve of them and get the tangent of that curve at any arbitrary point on the curve, then you will always find a point in the other curves where the tangent of this point is perpendicular to the tangent of the first point. My guess...
5. I Great Circle Distance Derivation

I derived the shortest distance between two points on a spherical surface (Great Circle Distance) , using the definition of the spherical coordinates and the dot product of the position vectors r1 and r2 where r1 = ( R cosθ1 cosφ1 , R cosθ1 sinφ1 , R sinθ1 ) r2 = ( R cosθ2 cosφ2 , R cosθ2 sinφ2...
6. Relativistic Calculations for De-Broglie Wavelength

Homework Statement At what energy will a non-relativistic calculation of the De Broglie wavelength of an electron be in error by 5%? What is this energy for a proton? Comment on your results. Homework Equations I have two (seemed to be) logical answers for this question, but with different...
7. Conditions in Wave Function, and Integration

I want to know how this integral will equal zero? I know that Ψ will fall to zero as x goes to infinity and i know that Ψ must fall to zero very quickly , Ψ must fall to zero faster than 1/√|x| all of this will help evaluating this integral i tried to solve it as follows The first term...
8. Transformers and iron cores and frequency

As far as i understand the thing that matter in all of the process of mutual inductance is the rate of change of the current in the primary coil $$\frac{dI}{dt}$$ butting soft iron core will increase the density of the magnetic field inside the primary coil, but how this will effect...
9. Relaxation time approximation and ideal hydrodynamics

Homework Statement please check attachment Homework Equations please check attachment The Attempt at a Solution since the deviation from f_0 to f is linear then we can write f=f_0 + C where C is some constant this should be enough to prove the first question (i think so) for the second...
10. Are Bathroom Scales geocentric?

i know that bathroom scales measures the normal force, hence the equivalence mass but if we took earth rotation into account then the normal force will be less by a value mv2/R according to this relation N = mg -mv2/R Example : a 70 kg man standing on a bathroom scale on the equator ...
11. Asymptotically stable node

Hi, i need a real world example of an asymptotically stable node, is there such a thing as asymptotically unstable node?
12. Uncertainty equal to zero

could we able to measure the velocity for a free particle with uncertainty equal to zero, could we able to have a certain values for its velocity, and let the uncertainty of the position to be infinity is there any theoretical restrictions on having a certain value for the velocity? is there...
13. Phase portrait for a conservative negative potential

Hi, i was studying Classical Mechanics course introduced by the brilliant Prof. V. Balakrishnan he was studying the phase portrait of a simple harmonic oscillator in one dimension , where the total enegry of the system is E=\frac{1}{2}m\dot{q}^{2}+\frac{1}{2}mω^{2}q^{2} where E is constant...
14. Radius of the electron and uncertainty

i thought that electrons are merely abstract thing or statistical entities, so i mitigated every attempt to visualize them as something that has a shape like a sphere, has a radius, internal structure, i thought that any attempt to measure a radius (if any) could result in uncertainty in...
15. Proper time problem

please read this problem "An astronaut traveling in a spaceship aims his flashlight to an object inside the spaceship, the beam of light moves on the same direction as the direction of motion of the ship, he observed the time interval between the light leaves the flashlight and when it hits...

17. Sound Propagation in liquids

Why sound waves propagate through liquids as longitudinal waves, and it is propagate on the surface of the liquid as transverse waves?
18. GRE E-Learning Solution

Hi, i need an E-Learning Solution for GRE Physics subject test is there such thing?
19. Capillarity action simulation

hi i need a software that allow me to test capillarity action in different shaped capillarity tubes please advise me
20. Hollow Conducting Sphere

A hollow, conducting sphere is initially uncharged. A positive charge, +q1, is placed inside the sphere (at the center). Then, a second positive charge, +q2, is placed near the sphere but outside it. Which of the following statements describes the net electric force on each charge? 1-There...
21. Wrong analysis in projectile problem

An archerfish shoots at a target 2.00 m away, at an angle of 30.0o above the horizontal. With what velocity must the water stream be launched if it is not to drop more than 3.00 cm vertically on its path to the target? i have troubles with this problem (Physics for scientists and engineers...
22. Alpha Tunneling

Hi, In case of alpha decay from Uranium atoms, i thought the barrier is the strong nuclear force, but i had seen many textbooks saying that it is electrical barrier, and i did rethink the subject and i imagined it as a barrier that have electrical force from one side and strong nuclear force...
23. Why Vectors product the way it is?

Hi, I am wondering why the scalar product of two vectors the way it is, i mean why it wasn't ABtanθ instead of ABcosθ, or XAB, while X is any constant value, why mathematicians define it that way, the same story goes on for the vector product, why we even had two types of products defined...
24. The Concept of Mass

Hi all I am wondering about the concept of Mass in physics. What does it mean? , why we have different concepts of mass? , Why scientists anciently proposed two concepts of mass, inertial mass and gravitational mass? , Why they wondered if they are equivalent, while if i was a one of their...
25. Programs Theoretical Physics Degree

Hello All i want to study theoretical physics and get a degree and then follow my post graduate studies, but i have to main problems, first is that i can't attend to much because i am working as a full time programmer so i need to find a reputable university that can offer the degree by long...