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  1. J

    Calculate the electric potential and field

    I tried it with no success.. I attempted to treat it like a ring of charge...finding E then integrating to find V. Still no success. I think I am getting lost in the "point any where on the axis inside or outside the tube". any suggestions how to solve this?
  2. J

    Electric Potential?

    Allow me to expand on what genneth started.. he is correct...E= - Del V where del is the gradiate operator. You have V in cartesian. so del V = x(hat)*dV/dx+y(hat)*dV/dy+z(hat)*dV/dz You text book should give the relationship for del V, don't forget the negative sign. So take the...
  3. J

    Calculate the electric potential and field

    Here is the question. a hollow, thin walled insulating cylinder of radius b and height h has charge Q uniformly distributed over its surface. Calculate the electric potential and field at all points along the z axis of the tube. Outside the tube Inside the tube. I know how to find the...
  4. J

    Derive expression for gradient operator in spherical coordinates

    Sort of I think I see what is going on...I have to take the partial derivative of each value with respect to the cooresponding value, r to x theta to x and phi to x, then r, theta, and phi to y and then to z...this in turn will provide the conversion, right? Is this essentially what how you...
  5. J

    Derive expression for gradient operator in spherical coordinates

    No...I have not covered that in my studies...I can read a little about. Any idea if I am even close with the way I am going?
  6. J

    Derive expression for gradient operator in spherical coordinates

    Do I have to do this for y and z? dT/dy= dT/dR*dR/dy+dT/d(theta)*d(theta)/dy+dT/d(phi)*d(phi)/dy dT/dz= dT/dR*dR/dz+dT/d(theta)*d(theta)/dz+dT/d(phi)*d(phi)/dz Then after this, its gets ugly, but I think this is how you do it... x^=R^(cos...)+theta^(cos...)-phi^(sin phi)...
  7. J

    Derive expression for gradient operator in spherical coordinates

    Correct so far? First, thanks for responding... Second, am I correct so far? Third, I don't quite understand what you mean, could you expand on that? Is it these values substitute into right hand side? x=R sin theta cos phi y=R sin theta sin phi z=R cos theta I am trying, but I...
  8. J

    Derive expression for gradient operator in spherical coordinates

    I need to derive the expression for the gradient operator in spherical coordinates. I know the following R =sqrt(x^2+y^2+z^2) theta, call it %, = arctan sqrt(x^2+y^2)/z phi, arctan (y/x) Using dT/dx= dT/dR*dr/dx+dT/d%*d%/dx+dT/dphi*dphi/dx, do partial derivates... dR/dx =...
  9. J

    Find basis for the kernel of linear map

    Got it... I was making it harder than it was... I solve for one of the variables, say a.... a=b+2c-d Then I plug this value into L. [b+2c-d, b,c,d] I could set up in aug matrix, but I can pull the constants b, c, d right out to get the kernel basis. Then my vectors are...
  10. J

    Find basis for the kernel of linear map

    I think I have it...if there is constants for artibary numbers then those constants make up the kernal and the other is the range, correct? SO if the the dim is 4 and the kernel is three, then the range is one... if I solve it for a=b+2c-d, then the kernal is the constants, b, c, d times...
  11. J

    Find basis for the kernel of linear map

    I need help. For this problem, you have to use the Gram-Schmidt process to make it orthogonal. My trouble is finding the bais for the kernel of the linear map L: R4 -> R1 defined by L([a,b,c,d)]=a-b-2c+d I know the dimension of the kernel is 3, but how? I have tried setting it...
  12. J

    Zener diode-finding Resistor value

    At least I'm not the only one that is confused why its 225...I'll keep digging...
  13. J

    Zener diode-finding Resistor value

    Need some help finding the value of the input Resister... Design a 7.5V zener regulator circuit using a 7.5 zener specified at 12 mA. The zener has an incremental resistance of 30 ohms and knee current of .5 mA. The regulator operates from a 10 V supply and has a 1.2 k-ohm load. What is the...
  14. J

    Linear Transformation

    Need some help getting started... Let T ={ [1, 0], [1, 1] }be a basis for R2 . Given that Transition matrix P s←t [ 2, 3 ; -1, 2], find the basis S for R2. Here is what I think...I started by letting v being any vector... [1,0] and [0,1] and applied them to the transition...
  15. J

    Span, Basis, Dimension

    I need some help to understand the concepts of span, basis, and dimension. 1-How do you determine if a set of vectors [in matrix form] span a region? -Do you set the given matrix set to arbitary numbers and see if there is a unique, infinite, or no solution? ie, set a 4X4...
  16. J

    Linear algebra

    Check me Can someone verify my signs are correct for when I solved, with help from the board?
  17. J

    Linear algebra

    ok...think i get it When I first did it, it didn't look right...almost too simple to be correct. Thanks for correcting me with my notation. my text does have a format but this doesn't support the large brackets required for a 4X1 matrix. I will try to make the matrix a little more easier...
  18. J

    Linear algebra

    still working with it... if I set u=a1, b1, c1, d1 and v=a1, b1, c1, d1 set L(u+v)=(this is what I get) [ (a1+a2)-(b1+b2) 0 (c1+c2)-(d1+d2) 0 ] which equals L(u)+L(v) for L(c*u)=c*L(u) [c(a-b) c*0 c(c-d) c*0] which converts to...
  19. J

    Linear algebra

    Alright... I am still trying to figure out this message board... I forgot to include what I already know... I know you have to prove that L(u+v)=L(u)+ L(v) and L(c*u)=c*L(u), but I don't understand how to set it up. I tried to separate it into a1 and a2, but just get confused... Do I...
  20. J

    Linear algebra

    I need some help solving this...not even sure how to start... Let L:R(4) goes to R(4) be the linear transformation defined by -matlab notation, the value is a 4x1 column L ( [ a b c d])=[ a-b 0 c-d 0 ] Show...
  21. J

    Potential barriers, etc.

    New some help with some problems. I have tried them an listed what I have done so far... 1. A beam of electrons is sent along the x axis from - with kinetic energy E=7.5eV. The beam encounters a potential barrier of height V'=1eV and width 2a=1.2nm. What fraction of the incident beam is...
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