Recent content by weeksy

ok so we would have I^2 = ∫∫e-x^2.y^2 dxdy i would love to know where this rule comes from, seems very weird that we can just introduce a function dependent only on x as f(x,y). and how do we know which order the dxdy goes?

Homework Statement Well iv been looking around for a similar problem and found the use of the following equation. what I would like to know is if the following equation is actually correct? I believe it may be a extension of the Fubini's theorem but can't find a reference or derivation on the...

your 100% right. dH=dU+pdV =TdS-pdV+pdV+Vdp =TdS+Vdp since dQ(rev)=TdS dH=dQ(rev) at at constant pressure since C_p=∂Q/∂T we have C_p=T(∂S/∂T) awesome thanks a bunch

I'm new to this forum, is there some sort of thanks button / points system to show appreciation ?

Ok very good Andrew, makes sense though seems a rather large implication that C_p is determined by a reversible process only. Oh and Darwin as I understand it entropy S is not defined by dQ=TdS for all conditions but dQ(rev)=TdS where (res) is for a reversible process only. Huge difference...

Just a quick question of something I found in my textbook but can't get how they produced it. C_p =(∂Q/∂T)_p that is the definition of heat capacity at a constant pressure p. Q is heat and T is temperature. This equation is fine and I know how to derive it. Now it is the next line which...

thank you very much.

I see, so we have 90-1/2phi =90-20.7 =69.3 degress and from this we can plug theata into the 2dsintheata=nlambda correct?

well the angle (phi) is the angle between incomming neutrons and reflected beem, and in our case phi= 41.4 degrees. So what am i missing? thank you very much for your patience.

Looking at the question again it states that the neutrons are hitting the plane normal ie at theata = 90 degrees which is the dotted line on that diagram right. Also we know the first maximum of the diffraction pattern occurs at a scattering angle (i.e angle between incoming neutrons and...

yeah its the drawing which is what is stuffing me up. when i draw a picture i have the neutrons comeing in at 90 degrees to the plane ie normal and the reflecting out at 41.4 degrees. but i don't think this is right?

Question-A certain crystal has a set of planes spaced 0.376 nm apart. A beam of neutrons strikes the crystal at normal incidence and the first maximum of the diffraction pattern occurs at a scattering angle (i.e angle between incoming neutrons and reflected beam) of 41.4 degrees. What is the de...