Homework Statement
The output of a sensor which produces 10000 electrons is connected to parallel RC circuit with Resistance= 50 ohm, and the capacitance=10pF.
Calculate the signal to noise ratio at temperature 300K.
Homework Equations
SNR= 10 log (power of signal/ power of noise)
Or...
Homework Statement
A hydrogen atom is identified as being in a state with n=4. What is the magnitude of the total orbital angular momentum for the largest permitted value of l?
Homework Equations
n>l, l is bigger or equal to m
The Attempt at a Solution
The allowed l= 3,2,1
The allowed m for...
BJT ,the output voltage is amplified because there is dc voltage supply to keep BJT active ,but what about the FET? The voltage supplied only control the gate only, anything to do with the output?
Thanks
To encode a symbol in binary form, I need 3 bits ,and I have 6 symbols.
So I need 6*3=18 bits to encode "We are" into binary form. As shown in http://www.shannonentropy.netmark.pl/calculate
My question: 3 bits to encode one then I have to use 16 bits, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
How to...
The following is the Planck's derivation for black body radiation
$${\rho}({\lambda}) d{\lambda}=E({\lambda})*f({E(\lambda}))*D({\lambda})d{\lambda}------equation 1$$
$$\int_0^\infty{\rho}({\lambda})d{\lambda}$$ is the density of radiative energy.
From...
$${\rho}({\lambda}) d{\lambda}=E({\lambda})*f({E(\lambda}))*D({\lambda})d{\lambda}$$
$${\rho}({\lambda}) d{\lambda}$$ is density of radiative energy,
$$E({\lambda})= k_BT$$ is the energy of an atom vibrate in 3D,
$$f({E(\lambda}))=1$$ is the probability distribution. Equals to 1 because we...
Dulong Petit use energy,E=$k_B$T and the probability distribution as f(E)=1.
Internal energy,u=3N$k_B$T
$$C_v=∂u/∂T=3NkT$$
Three there because there is 3 modes in each atom.
Then my question is why do we use E=kT?
I understand 1 atom has 3 degree of freedom,and 1 freedom has kT/2.
A...
Refractive index----- will it travel back along the same way?
From the picture
http://en.wikipedia.org/wiki/File:RefractionReflextion.svg
If I travel a light ray from n2 to n1 , I think the light ray will travel in the opposite direction shown in the first picture.
But what about the...
Homework Statement
Show in the graph ,there will be no allowed bound states with odd-parity if the well depth is less than ${V_min}$
Find ${V_min}$ in terms of k and a.where a is the half of the well width.
What does no allowed bound state mean?
Homework Equations
$cotz=-pa/z$ where p^2...
Reading from http://quantummechanics.ucsd.edu/ph130a/130_notes/node150.html
Again we have assumed a beam of definite momentum incident from the left and no wave incident from the right.
Why is the above statement made?
What does the reflected wave mean? There is now all why reflected...
Why the Griffiths book says : any function of x and t that depends on these variables in the special combination (x±vt) represent a wave of fixed profile, traveling in the -+x direction at speed v...
I don't really get the reason why from 2 terms of wavefunction can become only one term...
Homework Statement
How to get equation 1 from the thumbnail?
h1 h2 h3 doesn't have to be constant.
The most I can try is equation 2 .
Please guide thanks.
Homework Equations
The Attempt at a Solution
For infinite square well, ψ(x) square is the probability to find a particle inside the square well.
For hamornic oscillator, is that meant the particle behave like a spring? Why do we put the potential as 1/2 k(wx)^2 ?
Thanks
For commutator, HQ-QH = 0 .
But for this case as shown below, complex ψQHψ - HcomplexψQψ= 0?
If the operator Q is in term of (∂/∂t) and (∂/∂x) ,then the HQ-QH may not be zero.
Is there any restriction for Q operator?
<x>= ∫ complex ψ x ψ dx
How do we get this formula? And why must the complex ψ must be placed in front?
Please guide or any link to help,not really understand this makes me difficult to start in quantum mechanics.
Your help is really appreciated. Pls
Homework Statement
Find the moment of inertia of a rectangular plate of mass m, sides 2h and 2k , rotates about its diagonal.
Homework Equations
I= Ʃmr^2
The Attempt at a Solution
I=Ʃ m(x^2 +y^2) , let 2h parallel to x-axis, 2k parallel to y-axis. I= m(x cosθ)^2 + m (y cos ∅)^2 where...
Homework Statement
A=(x,3,1) ,B=(x,-x,2)
Determine the value of x if the vector perpendicular to A and B is given by C=(10,-4,-4)
Homework Equations
The Attempt at a Solution
Find A cross B , let A cross B be D . Then D cross C = zero (since they are perpendicular to both A and...
A magnet only attract ferromagnetic material because they have magnetic domains which will align to form magnetic dipole when external magnetic field applied.
Paramagnet dont have domains. Due to the presence of some unpaired electron, they will cause the realignment of the electron path when...
Homework Statement
A gun is shoot straight up. Assuming that the air drag on the bullet varies quadratically with speed, and the equation of motion for the bullet is (m/2)(dv^2/dx)= -mg-(cv^2).
Find for the downward motion , v^2 in terms of x.
Taking that upward direction is positive...
I think no matter what are the mass of two objects, there must be a fix angle between the angle of two direction.
Is that using the center mass reference to calculate?
I say that because we can prove that when the two objects with same mass collide, then the angle between the direction of the...
Homework Statement
I don't understand case 1. In case 2 that is normal integration , isn't?
Then why case 1 can simply ignore the r ? I don't think r is constant.
Homework Equations
The Attempt at a Solution
Please guide. Thanks
Homework Statement
The first equation on the uploaded paper converts to the last equation.
Homework Equations
when i substitute ln (1-u)=-u-(1/2)(u^2) into the first equation, i can get the first term in (3rd equation).
but the second term of the 3rd equation ?
The Attempt at a Solution
I...
How they know, how to see the spin of electron>??
Without external field applied, there is random dipole in the paramagnet.
for diamagnet, without external field , there will be no dipole exist.
Thanks.
http://www.answers.com/topic/radial-and-transverse-components
From the above link,
1) e θ is a unit vector perpendicular to r in the direction of increasing θ.
Where is the direction of increasing θ? Is that a circle? θ Increase from 0 to 2∏.then eθ moves in a circle? direction always...
Uncertainty--what is the rate with 0.59% precision??
Homework Statement
Assume that negligible uncertainty in timing of a clock, calculate the number of counts required to measure a rate with 0.50% precision.
Homework Equations
The least accuracy is 0.50%?
The Attempt at a Solution...