Recent content by madhavpr

Thanks Svein, for the reply. I was solving problems from a real analysis text. The problem looked like this. For a sequence of sets, E_n, (n=1,2,3,...), lim sup E_n = { x | x is an element of E_k for infinitely many k }. I don't understand the significance of this definition (and lim inf's...

Hi, I can derive a few properties of the limit inferior and limit superior of a sequence of sets but I have trouble in understanding what they actually mean. However, my understand of lim inf and lim sup of a sequence isn't all that bad. Is there a way to understand them intuitively (something...

While I do understand the story of the hypergeometric distribution, I was wondering if there's anything "geometric" about it, or if there's any connection between the distribution and "geometry". Can anyone throw some light on it? Thanks, Madhav

Thanks for the answer Shyan. That helps.

What is the relationship between transmission of information and group velocity of a wave packet? I always keep hearing things like information always travels at the group velocity, it can't go faster than light etc. While I do understand (to an extent) about information not exceeding the...

Thank you maajdl. So if I perform the same operation for the azimuthal angle, I can rule out that dependency. What's the fundamental difference between a) having a component along a particular unit vector (say z) b) being dependent on an independent variable (like z). For example, the...

Hi everyone. I don't know whether this is an advanced or introductory topic but I I've always wondered how to prove symmetry arguments in electrostatics, magnetostatics etc mathematically. Suppose you have an infinite line charge and you need to calculate the electric field at some distance...

I think I got it. But it looks more or less like a guesswork to me. Reversing the current is equivalent to turning my head 180 degrees and thus, I cannot have two radial components (in and out) of the B field. So the radial field has to be zero.

" What can you say about the the radial component of the field at all points inside the solenoid that are a distance d from the axis? " - Radial components at a distance d will point away from the axis. (If I assume a positive radial component of the magnetic field) Imagine turning the...

Hello TSny. I assumed a surface current pointing in the positive \phi (rotating counterclockwise) and calculated, by the Biot Savart law, a component of the magnetic field in the +s (Griffith's notation for the radial distance in cylindrical coordinates). I reversed the direction of...

Hi everyone. I'm having a relatively hard time in understanding Griffith's explanation of why the radial component of a magnetic field of a solenoid should be zero. He says, "If B(r) were positive, if we reversed the direction of the current, B(r) would be negative. But switching I is...