Recent content by Outrageous

  1. O

    Dulong Petit derivation.How do we get this formula?E=kT

    Is that because in an atom in a solid, there are 6 neighbors so, (6/2)${k_B}$ T
  2. O

    Signal to noise ratio for thermal and shot noise

    10000 electrons without telling time, but even telling time, I still can calculate the thermal and shot noise.
  3. O

    Signal to noise ratio for thermal and shot noise

    Yup, V =Q/C , and f=1/(2∏RC) But why is this the Bandwidth? The impedance of capacitor is same as resistance so we get maximum power for? And 10000 electrons need to consider shot noise? If I consider, so I just add thermal noise voltage and shot noise together to get the total voltage noise?
  4. O

    Signal to noise ratio for thermal and shot noise

    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...
  5. O

    Quantum mechanics , total orbital angular momentum?

    ##\vec{L}^2## mean the angular momentum square ##L_z## angular momentum in z direction ##\vec{L}^2##=l(l+1)\hbar and ##L_z##=m\hbar. Total orbit angular momentum is j? J=l-(1/2) or l+(1/2)
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    Quantum mechanics , total orbital angular momentum?

    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...
  7. O

    How does FET amplifier amplify?

    Thank you. If I want to calculate the output impedance, I have to off the input signal, yet there are still 2 dc supplies ,one to gate-source, another is the $V_cc$ , and there should be current pass though , but my book said $g_mV_{gs}$ =0? From the picture you gave,
  8. O

    How does FET amplifier amplify?

    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
  9. O

    Shannon entropy - use to calculate the bit needed to encode a symbol

    Thanks. Can you please give me some simple links to read??? Please
  10. O

    Shannon entropy - use to calculate the bit needed to encode a symbol

    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...
  11. O

    From Planck's law to derive the stefan Boltzman constant.

    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...
  12. O

    Derivation for black body radiation. What is the 2 bout?

    Can you please explain more? How two taps to empty a water tank? Water go from taps to tank then? How should I prove the two polarization modes? Please tell me. Thanks.
  13. O

    Derivation for black body radiation. What is the 2 bout?

    $${\rho}({\lambda}) d{\lambda}=E({\lambda})*f({E(\lambda}))*D({\lambda})d{\lambda}$$ $${\rho}({\lambda}) d{\lambda}$$ 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...
  14. O

    Dulong Petit derivation.How do we get this formula?E=kT

    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...
  15. O

    Refractive index- will it travel back along the same way?

    Sorry, it is spectrometer. Yup it is use to find the refractive index of the glass cell. My book says : a sharp boundary distinguishes the bright from the dark region because no rays are refracted with an angle of refraction larger than critical angle. So ? I think the refraction will occur...
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