« first day (2683 days earlier)      last day (238 days later) » 

pi-π
pi-π
08:23
Hey @JohnRennie!!
John Rennie
John Rennie
@pi-π Hi :-)
It's been a long time. How are doing these days?
pi-π
pi-π
@JohnRennie Doing computer engineering. How have you been?
John Rennie
John Rennie
Life goes on as usual, there are always more JEE students :-)
pi-π
pi-π
@JohnRennie Do you know how can we integrate Python in Dot Net Core ?
John Rennie
John Rennie
I've never used .Net Core ...
I use C# for some programs, but with an old version of .Net (I forget exactly which).
pi-π
pi-π
08:35
Okay. No worries.
John Rennie
John Rennie
I have no idea if there is any way to use the .Net framework from Python. It doesn't seem likely, but maybe someone has found a way to do it.
 
8 hours later…
sanya
sanya
16:05
Hi sir @JohnRennie
John Rennie
John Rennie
Hi :-)
sanya
sanya
To calculate force on a dipole in a non uniform Electric field the formula is (p.del operator )Electric field
I dont really understand the "del operator" part
John Rennie
John Rennie
Suppose you have a one dimensional problem where E is a function only of x. Then delE (often written as ∇E) is just dE/dx i.e. it's just the gradient of the field.
Suppose the dipole p was lined up with the field, making it effectively a 1D problem, then the force would just be:
F = p.dE/dx
@sanya OK so far?
sanya
sanya
Yes
John Rennie
John Rennie
The trouble is that we have to work in 3D, and in 3D the gradient of the field is a vector and it has the components:
∇E = (dE/dx, dE/dy, dE/dz)
The dipole is also a vector, with components p = (px, py, pz), and the force is the dot product of the two vectors.
p . E = (px, py, pz) . (dE/dx, dE/dy, dE/dz) = px.dE/dx + py.dE/dy + pz.dE/dz
Does this make sense so far?
sanya
sanya
16:15
Okay. So we are differentiating dE i w.r.t x ? dE j w.r.t x as well as dE k w.r.t x ?
John Rennie
John Rennie
Yes, exactly.
Oh wait, no.
dE j wrt y and dE k wrt z
del E = dE/dx i + dE/dy j + dE/dz k
sanya
sanya
Yes sry typo
Fx=px(dE/dx) Fy=py(dE/dx) Fz=pz(dE/dz)
But here they ve written
Cant upload image:( can you send me that link Where I can post it..?
John Rennie
John Rennie
swarchive.ratsauce.co.uk/.uploads
sanya
sanya
Done
John Rennie
John Rennie
user image
sanya
sanya
16:29
I don't understand isn't dE/dx already the x component of the field?
John Rennie
John Rennie
Yes OK it should be δE/δx not dE/dx
But it's the same thing i.e. differentiating E wrt x while treating y and as constants
Then doing the same for y and then z.
sanya
sanya
So shouldn't de_y/dx give us 0?
John Rennie
John Rennie
Oh wait, sorry ...
The picture is correct.
The x component of E can be a function of y and z as well as of x.
sanya
sanya
Oh so E in the x direction could change with change in position in the y or z dirn?
John Rennie
John Rennie
A simple example would be a point charge at the origin. The x component of the field at x = 1, y = 0 is not the same as at x=1, y = 1.
sanya
sanya
16:38
Oh
thankyou so much
John Rennie
John Rennie
You're welcome :-)

« first day (2683 days earlier)      last day (238 days later) »