Recent content by bmarson123

Homework Statement 224Ra --> 220Rn + \alpha 224Ra --> 212Pb + 12C 224Ra --> 210Pb + 14C Calculate the Q-Values (in MeV) for these decays given their atomic mass excesses (in MeV) are 88225Ra = 18.818 86220Rn = 10.604 82212Pb = -7.557 \alpha = 2.425 82210Pb = -14.743...

Homework Statement A doped silicon ingot is to be grown by the Czochralski technique with a dopant concentration of 1016boron atoms/cm3. If k0 = 0.9 for boron/Si, what concentration of boron atoms should be in the melt? Homework Equations Cs/C0 = k0 (1 - m/m0) k0-1 k0 = Cs / Cl The...

Homework Statement What is the Q value in units of MeV in each of the following processes? i) The spontaneous fission of 232U92 to 145La57 and 87Br35 ii) The neutron induced fission of 232U92 to 146La57 and 87Br35 Explain why heavy nuclei such as 232U92 do not usually undergo fission...

Figured it out! Forgot to convert the temperature to kelvin and then got everything written down in a mess!

Homework Statement An electric current of 10A runs for 1 minute through a 20 ohm Resistor which is maintained at 10 degC by being immersed in running water. What are the entropy changes in a) the resistor b) the running water c) the universe Homework Equations P = I2R dS = dQ/T...

Sorry, I get i) now. I've recalculated it and I've got (863.2, 0, -1151.0) N. Is that a more reasonable answer?

Also, why does r1 suddenly become negative? In the question you're told it's (3,0,0)m, so why does it become (-3,0,0) ?

Thanks so much for your help! I'm still a bit confused about i) I thought that if it wants the force on q1 then surely it should be the force of q2 on q1? Because otherwise it'll be the force q1 is excerting on q2? I did look at the link but it just confused me more, could you explain...

Homework Statement Consider a boundary between two dielectric media with dielectric constants \epsilon1 and \epsilon2 respectively. The boundary carries a surface charge density \sigma. Use appropriate integral forms of Maxwell equations and an illustrative sketch to derive continuity...

Homework Statement Two point charges q1 = 2\muC and q2 = -2\muC are placed at r1 = (3,0,0) m and r2 = (0,0,4)m respectively i) What is the force of q1 (in vector form)? ii) What is the electric field at the origin? iii) What is the electric dipole moment of this arrangement (in vector...

But what do I say after I've calculated the current density? I've got curl B = 2 j (j as in vector j) But what does that tell me anyway?

So for cases i) and ii) I can just say they are neither magnetic or magnetostatic, as it can't be magnetostatic if it isn't magnetic? Which means I only need to find the current density for iii)? I'm pretty sure I don't know how to do that, do I use curl B = \mu j ?

curl H = j + d D / dt ?? So is H the magnetostatic field?? And how can I apply that to this? Do I have to do curl of each field?

Homework Statement State whether the following arbitary fields can describe either a magnetic field, a magnetostatic field, neither, or both. In each case justify your answer: i) R(r) = R0 (x2,y2,z2) ii) S(r) = S0 (x, -z, y) iii) T(r) = T0 (-z, 0, x) Homework Equations div B=...

2.72 x10-10m?