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Everything posted by kidia

  1. I have a question here,A uniform doped n-type silicon substrate of 0.1ohm-cm resistivity is to be subjected to a boron diffusion with constant surface concetration of [math] 4.8*10^{-17} [/math] [math] cm^{3} [/math].The desired junction depth is [math] 2.8*10^{-6}m [/math].Calculate the impurity concetration for the boron diffusion as a function of distance from the surface and how long will it take to cover the distance if the temperature at which this diffusion is conducted is a 1100Cetigrade
  2. Please any idea on this one,Given the symmetric matrix [math] A=\begin{bmatrix}0&2&2\\2&0&2\\2&2&0\end{bmatrix} [/math] Find an orthogonal matrix P so that [math] PAP^{-1} [/math] is a diagonal matrix.
  3. Can anybody help me on this question,Show whether or not the following fields are conservative: E=y[math]z^2[/math][math]i[/math]+(X[math]z^2[/math]+2)j+(2xyz-1)k E=-([math]x^2[/math]-[math]y^2[/math])i-2xyj+4k I dont think if am right I want to start by comparing i follow by j and z,example y[math]z^2[/math]=-([math]x^2[/math]-[math]y^2[/math])
  4. Can anybody explain to me what and how a phase shifter can be implemented using BJT.or give me the site which can get more details about this.
  5. Can anyone help me on this question,Using [math]\epsilon[/math]-[math]\delta[/math] definition of a limit to show that [math]\lim[/math] [math]\frac {2x^3-y^3}{x^2+y^2}[/math] = 0 (x,y)[math]\rightarrow[/math](0,0)
  6. I have a question here I will appreciate for any idea,The mean of distribution is 5.The second and third moments about the mean are 20 and 140 respectively.Find the moment of the distribution about 10.
  7. I have one question here,I fail to understood what is Q of the system,is anybody has an ideal on this? An object of mass 2 kg hangs from spring of negligible mass. The spring is extended by 2.5 cm when the object is attached. The top end of the spring is oscillated up and down in SHM with amplitude of 1 mm. The Q of the system is 15. What is angular frequency for this system?
  8. Can anybody give me the hint where to start on this question? Two simple harmonic oscillators of the same frequency and in the same direction having amplitudes 5 mm and 3 mm, respectively and the phase of the second component relative to the first is 30°, are superimposed. Find the amplitude of the resultant oscillation and its phase relative to the first component.
  9. kidia

    Air Condition

    What about oxygen,does it play any role in bringing oxygen or fresh air from outside?
  10. kidia

    Air Condition

    I have very basic question, one function of domestic air condition is to cool air can any body tell me other functions more than that?
  11. I have a question here A rectangular plane loop with dimensions 250 mm by 180 mm is pivoted to rotate about the z axis. The long side of the loop is along the y-axis and the plane of the loop makes an angle of 45 degrees with the y-axis. If a uniform magnetic field of magnitude 300 mT is in the y direction: (a) Determine the magnitude and direction of the force of each side of the loop. (b) Determine the torque about the z axis. I know that F=BILsin theta and Torque=BAIsin theta my problem here is how to get the current I
  12. How can I Compare the magnitudes near the earth’s surface of the weight of an electron and a typical magnetic force exerted by the earth’s magnetic field (B = 10-5T) on an electron with speed 10 m/s. As I understood Weight of electron = mg Magnetic force=qBv am I right?
  13. Thanx,cross products I learned it in mathematics.
  14. How please Klaynos clarify.
  15. Please can anybody help me on this? The magnetic force on a moving electric point charge is given by F=qv*B where v is the velocity of the charge q and B the magnetic field. Derive the components of the magnetic force Fx, Fy, and Fz.
  16. Can anybody explain to me why holes are found at the top of the valence band, whereas electrons are found at the bottom of the conduction band.
  17. Anyone can help me on this one. A plane wave of wavelength [math]\lambda[/math]= 550 nm is incident normally on an opaque screen with three narrow parallel slits separated by distance [math]a[/math]= 2.3 mm. An interference pattern is observed on the other side of the screen at a large distance from it. (a)At what angles are the first principal maxima adjacent to the central maximum? (b)How does intensity, Imax, at the principal maxima compare to that from a single slit, I1? in (a) can I use asin[math]\theta[/math]=m[math]\lambda[/math] to get the angle?
  18. kidia

    Order Number

    My problem on this question is that I dont have a diffraction angle. A grating with 1500 slits per centimeter is illuminated with a light of wavelength 500 nm. What is the highest – order number that can be observed with this grating?
  19. kidia


    OK,from your point ,if we take another similar example of sound waves abtained by driving two different loudspeakers from the same audio source They may be in phase, then again they may not be.Because we have different speakers,different amounts of dirt and stuff on them,IS IT?
  20. kidia

    Pointing Vector

    Can anybody give me the physical meaning of the pointing vector S=EXE for time varying fields. What are its units?
  21. kidia


    Remember that headlights always coming from same light source how can it be incoherent?
  22. So is acceptable that ribs act as a diffraction grating for the X–rays
  23. You mean that the diffraction granting cannot take place in a few centimeters?
  24. When you receive a chest X–ray at a hospital, the X–rays pass through a series of parallel ribs in your chest. Do the ribs act as a diffraction grating for the X–rays? Why?
  25. kidia


    I have one question here which I need clarification. Automobile has two headlights. What sort of interference pattern do you expect to see from them?
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