Recent content by pilotguy

Homework Statement A line charge λ is surrounded by a long cylindrical insulator with a linear charge density 2λ and radius a. This is surrounded by a concentric conductor cylinder of radius b. Use Gauss’s Law to find the charge density on the surface per unit length at r = a just inside...

I'm not sure; the question is a little ambiguous on that. Does it make a difference to the solution from earlier in the thread?

Yeah, I noticed that. I tried it with the correct conversion (.356 m) and 5577 amps was what I found for current. Isn't that really high though?

Except that gives a current of 5577 amps for the second part. What am I missing?

Hmm. Density of Cu=8.96 g/cm^3 (8.96g/cm^3 * 1 / 10g)^-1=1.119 cm^3 Ohh, that gives you a volume! D'oh! V=1.119 cm^3 1.119=pi*r^2*L L=1.119/(pi*.1^2) L=35.605 cm So, R=rho(L/A) R=(1.899*10^-8)(.0356)/(3.142*10^-6) R=2.152*10^-4 ohms Does this sound right?

Homework Statement A 10-g piece of copper is to be formed into a wire of radius 1.0 mm at a temperature of 50° C. What is the resistance of this wire? (Hint: you will need to look up the density of copper.) If a potential of 12 V is put across this wire, what is the drift velocity...

Perfect! Thanks for the help!

I see. Any guess as to what was my professor trying to get at with his hint about the discriminant in the quadratic equation?

So there's no equilibrium between them; does that mean that there's only equilibrium at +/- infinity? That would reduce the force to essentially zero. I'm a little lost.

Oh, I think I see what you're saying. If the + charge is on the left, and the - charge is on the right, with a positive test charge between them, the test charge will be repelled from the positive charge and attracted toward the negative charge, meaning that both forces would act to the right...

So does that mean that it's Frep=ke*(q'*q+)/x^2 and Fattr=ke*(q'*q-)/(d-x)^2? Then equate them and solve for x?

Homework Statement Take two charges, one positive with charge q+, and another with charge q- are at a distance d away from each other. Under what conditions is there a point of equilibrium and, if it exists, where would it be located? Show mathematically. (Hint: use the quadratic equation...