Recent content by Kudo Shinichi

  1. K

    Magnetic Field Calculations for Parallel Wires

    a)r=14.14 The magnetic field for B is 1.132x10^-6 and it is moving upward I think that I have misread the question for part B, I just need to find out the magnetic field of the lower left point and use the force equation F=current times magnetic field times length to find out the force for the...
  2. K

    Magnetic Field Calculations for Parallel Wires

    Homework Statement Four long copper wires are parallel to each other, their cross sections forming the corners of a square with sides a=20cm. A 20A current exists in each wire in the direction shown in the diagram. http://i41.tinypic.com/2uiw6ck.jpg a) What are the magnitude and direction of...
  3. K

    A Magnetic Field Problem with a Triangular Loop

    I have re-read the textbook again, and I found out that the direction of the force is always perpendicular to the B, and if you use the right-hand rule, fingers point straight along the current and bend to get B, which means that B is also perpendicular to current...so I am kind of confused now...
  4. K

    A Magnetic Field Problem with a Triangular Loop

    a)F=current x length x uniform magnetic field x sinθ x-direction: F=(-i x B x sqrt(l^2+l^2))+(i x B x l x sin 45) + (i x B x cos 45) y-direction: F=(-i x B x l)+(i x B x l x cos45)+(i x B x l x tan45) b) direction of magnetic dipole moment: 45 degree respect to the horizontal negative...
  5. K

    A Magnetic Field Problem with a Triangular Loop

    Homework Statement A current i flows through a triangular loop in the y-z plane. The loop is situated in a uniform magnetic field B. http://s5.tinypic.com/14csew3.jpg a) Find the total force on the loop when the magnetic field is in i) the x-direction, and ii) the y-direction b) What is the...
  6. K

    A question on determine the rate of formation (chemistry)

    Homework Statement For the reaction A-->2B+C, the following data are obtained for [A] as a function of time: t=0min, [A]=0.80M; 8min, 0.60M; 24min, 0.35M; 40min, 0.20M. Calculate the rate of formation of B at t= 28 min. The Attempt at a Solution I have found out that this equation is a first...
  7. K

    A question on finding the resistance from a 3D cube

    Sorry, I don't really get what you were saying... I think that all the eight points have the same potential and should since there are no extra battery in the circuit. should I connect all the point diagonally with wires? but the question says each side of the cube has the resistance of r and i...
  8. K

    A question on finding the resistance from a 3D cube

    Homework Statement Find the resistance between the points a and b for the resistor network shown. http://s5.tinypic.com/1073kvd.jpg The Attempt at a Solution I changed to 3D cube into a 1D square and each side of the square contains 3r because each side of the cube contains an r(for...
  9. K

    A question on alternating current

    Homework Statement The peak value of an alternating current in a 1500W device is 5.4A. What is the rms voltage (root-mean-square voltage)across it? The Attempt at a Solution Peak current=sqrt(2)*Irms 5.4A=sqrt(2)*Irms Irms=3.82A Irms=P/Vrms 3.82=1500/Vrms Vrms=392.84V I am not sure...
  10. K

    HELP A problem on quantitative aspects of electrolysis

    there are 0.052 moles of copper 0.103 moles of electrons (2 electrons transferred in copper) I am not really sure about the moles of hydrogen gas but since there are 2 moles of electrons and 1 moles of hydrogen gas, I think that the moles of hydrogen gas is 1/2 of the moles of electrons...
  11. K

    HELP A problem on quantitative aspects of electrolysis

    HELP!A problem on quantitative aspects of electrolysis Homework Statement A quantity of electric charge brings about the deposition of 3.34 g Cu at a cathode during the electrolysis of a solution containing Cu2+(aq). What volume of H2(g) measured at 27.8oC and 767 mmHg, would be produced by...
  12. K

    How Can You Create a Temperature-Independent Resistor Combination?

    Sorry, but I still think that DT should be 0-20=-20, because the values of α for both copper and nichrome are at 20 degree celsius. Or do you mean radomly select numbers and plug into the equation to solve the problem? However, I don't really know how to solve the problem in this way... I...
  13. K

    How Can You Create a Temperature-Independent Resistor Combination?

    Do you mean that R=[1+α(T-To)] for both carbon and nichrome resistor? α for carbon resistor is -0.0005 and α for nichrome resistor is 0.0004 If R=[1+α(T-To)], then R for carbon would be 1.01 and R for nichrome would be 0.992 where T=0 and To=20 since we are trying to find the resistance at...
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