What is the source of the electric field in a RF cavity that causes particle acceleration? Charged particles are accelerated through a RF cavity:  -Is the electric field accelerating the particles from the electromagnetic field itself?  -Or, is the electric field accelerating the particles from charges on the surface of the conductive cavity being moved to form a capacitor by interaction with the electromagnetic field?
Accelerating electrons via microwaves In Synchrotrons I think they use microwaves to accelerate the electrons bundles that fly through-how does putting a microwave through a cavity accelerate an electron? I know that the Electric and Magnetic fields could and do have an effect on the electron, but if the radiation is moving parallel to the electron, wouldn't the force be perpendicular? Also, how exactly does the microwave radiation look in the vacuum chamber? Are the two ends constant nodes?
Change the folder that Windows Explorer starts at In Windows7, when you open the Windows Explorer using the pinned Windows Explorer button on taskbar, it opens WE and points it to My Documents folder.  Is there a way to change this so it doesn't open My Documents, but rather "Computer" just as Windows+E keyboard shortcut does? This week I've read two news stories about two different camera lenses that can magnify things that are very far away.  The first is the , which is a point-and-shoot camera that costs $600, has an 83x optical superzoom lens ("the same field of view as a 2,000mm lens on a full-frame camera"), and lets you see the craters of the moon.  The second is the , which weighs 36 pounds, costs $180,000, and can take portraits of people a half mile away.  A non-photographer might ask, "Why would somebody spend their life savings on a gigantic telescope of a lens when you could take far away pictures with a handheld camera for 1/300th the price?"  Well, I am basically a non-photographer, and I would like to ask that question. What does the big one give you that the little one doesn't provide? I understand that small changes in lenses can make a big difference in size and price, but this seems to be of a different scale entirely.   What is going on with the optics of the lenses that makes the small one able to be so small and the big one have to be so...big?   I'm trying to get a basic intuition for what makes lenses different, and I realize I don't understand enough about how lenses work to even know how to compare these apples and watermelons. javax.faces.application.ViewExpiredException: View could not be restored launch an exe/process with stdin stdout and stderr? Mac renames itself automatically - host name is incorrect in terminal I've got a handleful of macs (all with unique names) and on occasion it prompt a notice about saying another computer on the network as this name and adds a (2) or (3) to my mac.    How can I set the host name from the command line? Is there any way other than instanceof operator for object type comparison in java? I remember reading in some Java book about any operator other than 'instanceof' for comparing the type hierarchy between two objects.  instanceof is the most used and common. I am not able to recall clearly whether there is indeed another way of doing that or not. Proof of for-all / there-exists "negation"? Switching to different font size(s) locally I've just finished running my first session with only one player, and it felt pretty different from running a session for a group.  Could someone with more experience in this talk about what one should do differently in that situation?  I'm not referring to mechanics like encounter-building, but just how to handle the change to the social dynamics. What happens if you use the 32-bit int 0x80 Linux ABI in 64-bit code? The definition of "Lie group" typically restricts to a smooth manifold.  If we instead define a "Lie group" to be a topological manifold such that multiplication and inversion are continuous, is the manifold necessarily smooth?  Is the smooth structure unique if we want a smooth Lie group?  I believe the answer is yes, since a connected Lie group structure is determined by the Lie algebra, but my search attempts failed. Is it true that for each set $M$ a given injective function $f: M \rightarrow M$ is surjective, too?  Can someone explain why it is true or not and give an example? I was wondering if there was any was I could right click inside any instance of a "Finder" window such that I have an option that says "Open Terminal Here". It would be really helpful. Writing C# debug output to .txt file I'd like to estimate the correlation between:  An ordinal variable: subjects are asked to rate their preference for 6 types of fruit on a 1-5 scale (ranging from very disgusting to very tasty) On average subjects use only 3 points of the scale.  A continuous variable: the same subjects are asked to quickly identify these fruits, which results in an mean accuracy for the 6 fruits.   Is Spearman rho the best method to analyze these data and/or are there other good methods I could consider? Calendar.getInstance(TimeZone.getTimeZone("UTC")) is not returning UTC time Is there a good reason for the removal of this FrameTicks syntax? What happens when I connect a 2 amp charger instead of the 0.7 amp charger provided? Possible Duplicate:             I have a phone with 0.7 amp charger. I also have a Galaxy Nexus with a 2 amp charger.  If I connect the 2 amp charger into my phone, will my phone blow up? Normality of subgroups and Sylow groups under homomorphisms... Prove or disprove: if $f:G \rightarrow H$ is a surjective group homomorphism, then   1) $f(A)$ normal implies $A$ normal.  2) $S$ is a p-Sylow subgroup of $G$ implies $f(S)$ is a Sylow-p subgroup of $H$.   I believe 1 is false since I believe we need injectivity, but I cannot think of a counterexample...  I believe 2 is true but do not know how to show it... I created a custom module in drupal 8. And I am trying to add js and css file in  my_module.libraries.yml file using this   lrv_key:   version: 1.x   js:     js/lrv.js: {}        dependencies:       - core/jquery       - core/drupalSettings   css:     theme:       css/lrv.css: {}   But it doesnt work.