Recent content by albega

Well I originally put (∂p/∂T)S>dp/dT in the original post but that was because I was imagining p,T increasing along the adiabat whereas they would fall in an expansion... So I'm not quite seeing it. Despite this, the actual mathematical condition I have to find is Cp,liq+Td(L/T)/dT<0, but I...

Gradient of adiabat<gradient of phase boundary, or (∂p/∂T)S<dp/dT at the crossover point?

Answers in order: dp/dT=pL/RT2 Also if I treat it as an ideal gas I have L=L0+ΔCpT, giving p=p0exp[(ΔCplnT-L0)/T/R], which may be helpful? Ok so if you look at the phase boundary in the p-T plane, we have a liquid region at higher pressures and a gas region at lower pressures separated by the...

Clausius Clapeyron equation: dp/dT=L/TVvap Adiabatic expansion of an ideal gas: p1-yTy=constant where y is the adiabatic index Not too sure where to go though...

Homework Statement In an earlier part of the question, I derived the temperature dependence of the latent heat of vapourisation of a liquid as dL/dT=L/T+ΔCp-L/Vvap(∂Vvap/∂T)p I am asked to find the condition that upon expanding the gas adiabatically, we get condensation to occur, by considering...

7 Ok, I didn't think about that very well - so I believe we want Δ/2+(2m+1)π=6.5Δ for integer m, so then Δ=(2m+1)π/6, θ=(2m+1)λ/12d. These are equally spaced. Angular width is then λ/6d. Uncovered case, minima when nΔ=2mπ θ=mλ/8d for integer m but for m=8r for integer r. Again equally spaced...

So for your n=8 case, if I draw the phasors for the case where the middle n/2 are covered, then we can split them up into two parts. The first two slits give two phasors, with overall phase Δ/2. The last two slts give two phasors with overall phase 6Δ+Δ/2=6.5Δ. Now I want the resultants of these...

Thanks for your reply - yes you assumed right - n/4 uncovered then n/2 covered and then n/4 uncovered. Ok, I understand what you mean by your conditions, but then how would you go about converting them into mathematical expressions in order to get the angles of the minima? I'm having trouble...

Note from mentor: This thread was originally posted in a non-homework forum, so it does not use the homework template. -------------- We have n slits, however suppose half of the middle ones are covered. How could you go about finding the angles at which the minima occur at in the Fraunhofer...

When superposing waves in say double slit interference from two slits, I seem to have come across two approaches: 1. Sum the two waves in complex form to get the resultant amplitude, take the real part, and square to get the intensity, i.e I=[Re(A)]2 2. Sum the two waves in complex form to get...

Standard temperature, 0degc. Thanks.

Homework Statement What is the mean free path of an N2 molecule in an ultra-high-vacuum chamber at a pressure of 10-10mbar? Homework Equations λ=1/(√2)nσ number density n, collision cross-section σ p=nkT pressure p, temperature T σ=πd2 d molecular diameter The Attempt at a Solution...

Thanks - this was the sort of thing I wanted... I managed to satisfy myself before seeing this anyway by imagining freezing all the particles, bringing them to my origin and then letting them go, which is similar to what you said.

Why should it not be surprising? I suppose I'm mostly confused about 'if all molecules are equally likely to be traveling in any direction, the fraction whose trajectories lie in an elemental solid angle dΩ is dΩ/4π' now. What does it actually mean, to say have a gas in a volume, choose some...

But the fraction whose trajectories lie in an elemental solid angle dΩ is dΩ/4π, so at θ=0 the fraction is zero and at θ=π/2 the fraction is non-zero. I don't understand how that is because of the coordinates?