Post your questions that don't deserve their own thread in here.
Tips for good questions:
>provide context
>check stackexchange first
>if stuck half-way into a question, show your work so far
Previous thread:
Which vitamin/nutrient deficiencies can be self-diagnosed relatively easily/cheaply?
fat jon snow
I need solid problems on electromagnetism, electric fields and waves.
pls help.
will post hot mongolian figure skater as a rewars
...
Does anyone know how I would solve these questions, I can't figure out if i'm supposed to set it up using an integral or how I would find the total amount of water from the tank.
How do I go about integrating [eqn] -\frac { 1 } { 4 } \int d^4 x \left ( F_ { \mu \nu } \right ) ^2 [/eqn] P&S says that it's [eqn] \frac { 1 } { 2 } \int d^4 x A_{ \mu } ( x ) \left ( \partial ^2 g^{ \mu \nu } + k^{ \mu } k^ { \nu } \right ) A_{ \nu } ( x ) [/eqn]Unless I've missed something the only way I can see to do it is to write it out and integrate term by term.
First time reading this.
I know this is going to sound bad but, what regime do you guys follow when doing exercises?
All of them before next chapter? Odd numbered only? How many exactly?
Its not that I wouldn't like to do them but... there's a shitload of them and I would like to finish the book someday so can I get a recommendation?
youtube.com
Somewhat funny.
Jackson is a good start, as user above suggested. You could also just google any applied EM book for inspiration. It's hard to recommend something unless you make your request a tad more precise.
Integral, yes. In a) you just integrate it (ans = -360). In b) you should divide your time interval into the periods where V' is monotonic, and then just add up absolute values (ans = 920). In c) you just find how much water has flowed out until it started to fill (at t = 2 sec, dV = -640, V = 60). For d) it is t=0 // V=700, and e) is just the indefinite integral of V'.
I would just go to momentum space where it is (almost) trivial. Or use a better book, I fucking hate Peskin/Schroeder with a passion. Srednicki, for instance, comes with a solution manual.
Define a binary operation [math]\star[/math] on [math]\mathbb{Q}[/math] by [math]a\star b = (a-2)(b-2)[/math]. Find [math]\star[/math]'s identity, if it exists, and state which elements are invertible.
As far as I can tell, there is no inverse, as the formula for an inverse to [math]a[/math] is [math]\frac{3a-4}{a-2}[/math], and an inverse has to be constant. But this would mean no elements are invertible, which makes the second part of the question pointless. Am I missing something?