OOTS #1300 - The Discussion Thread

[brian 333]

Due to the urgency of dealing with a critically dangerous opponent (the dragon) my plan was to deal with that by whatever means and take care of the logistical problems afterward.

I wonder if bite-sized Blood feast can chomp down on Calder's uvula and hang on? Prevent all but silent spellcasting, prevent breathing, (and breath weaponing,) and choke the dragon all at once.

[Kish]

Or... the rules as written are using the wrong model.

Wut?

Sorry, but one thing I am quite certain OotS is not based on, is "gbaji's house rules."

(I thought knowingly quoting 5ed and saying some variation on: this is relevant here because I bet 3.5 does the same thing, not bothering to look, but I bet! was baffling. This manages to be much worse.)

[Quizatzhaderac]

My two cents.

Except things in a Faraday Cage, which provides protection from EMF in distinct frequency bands, depending on the weave, materials, and volume of the cage. So, things within the 'cover' of the Faraday Cage are unaffected by external electromagnetic force, and if the point from which the EMF emanates is behind a Faraday Cage from the PoV of an object, that object is shadowed by the cage.

Exactly like the AMF description, except that more things affect the AMF than an EMF field.

A faraday cage blocks particles (photons), not the EM field; blocking a simple electric field is literally impossible.

[gbaji]

Why would you assume your interpretation would be right without reading the rules?

Because I'm reading the actual spell description:

An invisible barrier surrounds you and moves with you. The space within this barrier is impervious to most magical effects, including spells, spell-like abilities, and supernatural abilities. Likewise, it prevents the functioning of any magic items or spells within its confines.

An antimagic field suppresses any spell or magical effect used within, brought into, or cast into the area, but does not dispel it. Time spent within an antimagic field counts against the suppressed spell’s duration.

I'm sorry. But if I'm told that the spell creates an "invisible barrier" 10' in radius, centered on me, I assume there's an actual barrier there (tangible or not). And if the spell description further sates that "the space within this barrier <has effect listed>", I'm going to be this crazy silly person who assumes that the barrier defines the area of effect, and that every single space within that barrier is affected by said effect. Because... wait for it... that's precisely what the spell description says.

The only way you get to the whole "it's emanating from the center and is blocked by physical objects" is litearally noticing the word "emanation" in the effect line of the spell, then looking up what that means in the rules somewhere else. Then thinking "huh. That's not at all how I thoiught the spell should work".

It's a fairly obvious case of re-use of mechanical rules applied to a spell that doesn't really match the more common use of similarly shaped area effects.

And what about Anti-magic Field makes it obviously penetrate anything when almost nothing else does?

Because it's a field, and already has a clearly defined boundary for the field in the spell description? Also, the fact that it's not actually affecting the objects in the area, but the area itself (more specifically any active magic effects within the area).

The rules are clear, and consistent, and there's nothing I see in the rules or fluff that makes it obvious that the spell should hit everything within range regardless of cover. Why does he think that this spell penetrates absolutely everything but fireball doesn't?

Because a fireball affects the surface of the objects struck, with fire damage. An antimagic field, doesn't just affect the surface of the objects "struck" by some kind of emanation from a center point, right? If that were the case, then Bloodfeats skin would revert to full sized dino, while everything else remained a polymophed lizard.

This interpretation of the spell effect forces us to consider a host of odd scenarios, with no clear rule to follow. It's the opposite of "clear and consistent". How far through a solid object does the AMF penetrate? One inch? A half inch? Not at all? What if I hold a sheet in front of me? Can I cast spells normally? What if I wear the same sheet? Does it now count as clothing and not protect me? What if I'm lying in bed and hiding under the same sheet? Protected, or not protected? I could literally sit here listing of odd edge cases and how they don't make sense all day long, but hopefully you get the point.

My ruling? Very clear. If it's inside the area, no magic works except for those generated by artifacts or deities. Period. Done. No confusion at all.

The "technically by the letter of the rules" ruling? A completely incoherent set of nonsense that we have to constantly stop and argue over.

I'll take my ruling.

And the "actual" field under discussion here a cone projected by an eye-thingy's big central eye. Why would anyone's default assumption be that a cone from the eye can penatrate an opaque barrier? Eye's and not going through barriers strikes me as the obvious intuitive way for it to work.

So? This is not a medusa's gaze, where it being able to see you (or you see it) is what makes it work. And what about transparent barriers? I hold up a sheet of glass, and the antimagic field stops there. It has nothing to do with the source being an eye. It's about the nature of the effect in question.


To me there's no reason to assume that an antimagic field should not penetrate through all objects in the area, and it honestly makes a heck of a lot more sense as well. This is not a physical thing. It's purely magic, and only affects magic. Why on earth would a solid object block that?

[KorvinStarmast]

Because I'm reading the actual spell description:

An invisible barrier surrounds you and moves with you. The space within this barrier is impervious to most magical effects, including spells, spell-like abilities, and supernatural abilities. Likewise, it prevents the functioning of any magic items or spells within its confines.

An antimagic field suppresses any spell or magical effect used within, brought into, or cast into the area, but does not dispel it. Time spent within an antimagic field counts against the suppressed spell’s duration.

I'm sorry. But if I'm told that the spell creates an "invisible barrier" 10' in radius, centered on me, I assume there's an actual barrier there (tangible or not). And if the spell description further sates that "the space within this barrier <has effect listed>", I'm going to be this crazy silly person who assumes that the barrier defines the area of effect, and that every single space within that barrier is affected by said effect. Because... wait for it... that's precisely what the spell description says.

The only way you get to the whole "it's emanating from the center and is blocked by physical objects" is litearally noticing the word "emanation" in the effect line of the spell, then looking up what that means in the rules somewhere else. Then thinking "huh. That's not at all how I thoiught the spell should work".

Isn't the Beholder's anti- magic ray an emanation? From the Beholder? (Which is Sunny's creature type, regardless of the lawyers. We'll refer to him as a naive-gaping-floating-orb-with-stalks if necessary).

[brian 333]

My two cents.

A faraday cage blocks particles (photons), not the EM field; blocking a simple electric field is literally impossible.

Michael Faraday and Joseph Henry disagree with you.

[Kish]

Isn't the Beholder's anti- magic ray an emanation? From the Beholder?

Thanks for pointing that out. It is, I think, quite significant that all this dogmatic asserting that everyone must find the actual letter of the rules hugely counterintuitive ignores the fact that whatever might be the case when the ancient black dragon cast the spell Anti-Magic Field, what's currently under discussion is very clearly an emanation, and one with an obvious logical association with sight (it comes from an eye) to boot.

[Mordar]

Thanks for pointing that out. It is, I think, quite significant that all this dogmatic asserting that everyone must find the actual letter of the rules hugely counterintuitive ignores the fact that whatever might be the case when the ancient black dragon cast the spell Anti-Magic Field, what's currently under discussion is very clearly an emanation, and one with an obvious logical association with sight (it comes from an eye) to boot.

I don't know how much to read into this...

But strip #1298 p3 shows V and the space behind Calder/V in the colored effect, and in p4 V is dropping because of flight suppression. Now it may be that V is offset sufficiently that Sunny has LoS on both V and Calder, and with the comic being 2D we have no way of seeing a shadowing of the anti-magic effect.

However, P5 shows Calder, a very large dragon with a significant percentage of its body between V and Sunny, catching V while still in the anti-magic color effect. Similarly, page 2 P 3 shows the same thing.

As such, I believe the visual evidence is sufficient to clearly indicate the anti-magic eye beam is not adversely impacted by a large body being in the way of that beam (e.g. no shadow, or LoS limitation at least not such that a giant dragon body blocks normal LoS).

See also: Bloodfeast not blocking the anti-magic effect in the famed GLRKT! panel.

- M

[KorvinStarmast]

But strip #1298 p3 shows V and the space behind Calder/V in the colored effect, and in p4 V is dropping because of flight suppression. Now it may be that V is offset sufficiently that Sunny has LoS on both V and Calder, and with the comic being 2D we have no way of seeing a shadowing of the anti-magic effect.

Yes. Think in 3 dimensions. V falling means V was offset enough to get hit.

However, P5 shows Calder, a very large dragon with a significant percentage of its body between V and Sunny, catching V while still in the anti-magic color effect. Similarly, page 2 P 3 shows the same thing.

But V fell, which changes the spatial relationship ... in three dimensions.

As such, I believe the visual evidence is sufficient to clearly indicate the anti-magic eye beam is not adversely impacted by a large body being in the way of that beam (e.g. no shadow, or LoS limitation at least not such that a giant dragon body blocks normal LoS).

Do not concur. If a bit of the three dimensional cone (think Dunce Cap) hits you then the magic is suppressed.

See also: Bloodfeast not blocking the anti-magic effect in the famed GLRKT! panel.

Only blocked part of the cone, not all of it.

That's my take.

[danielxcutter]

And what about Anti-magic Field makes it obviously penetrate anything when almost nothing else does?

The rules are clear, and consistent, and there's nothing I see in the rules or fluff that makes it obvious that the spell should hit everything within range regardless of cover. Why does he think that this spell penetrates absolutely everything but fireball doesn't?

And the "actual" field under discussion here a cone projected by an eye-thingy's big central eye. Why would anyone's default assumption be that a cone from the eye can penatrate an opaque barrier? Eye's and not going through barriers strikes me as the obvious intuitive way for it to work.

Because I'm reading the actual spell description:

I post one thing and both sides of the argument (even the one I agree with) say I’m wrong, why do I even bother.

[brian 333]

Why would you assume your interpretation would be right without reading the rules?

The spell description says the spell effect is an emanation, but nowhere in the text of the spell does it describe what that means. You have to go to the spellcasting rules for that, not the spell description.

Therefore, a certain part of the audience sees 'Field' in the spell name, deduces that it is a zone effect regardless of the line of effect and cover rules, (as admittedly I have done until a few weeks ago,) and are now using 'logic' to determine that the rules are wrong. (Logically, why does Melf's Arrow not require a bow to fire it?)

Then there is the other extreme, who say that it is obvious that the eye-creature must see the target for the antimagic to affect it. To them, it is perfectly clear that no reading of the rules is necessary for what is basic logic.

But both sides are advocating the premise that their logical deduction is simple, based on the in-comic evidence, and correct. And both sides ignore that the logic of the other side leads to a different conclusion. How can logic lead us astray? Mr. Spock! Where are you when we need you?

But your point is exactly the missing link. When a disagreement comes up, refer to the rules. Not just the spell description, but the spellcasting rules in general.

So, what do the rules say?"An Emanation spell functions like a burst spell...
...It can't affect creatures with total cover from its point of origin. (In other words, its effects don't extend around corners.)"

The rules do not require the target to be visible. But line of effect to the point of origin must be possible. "... Emanation affects an area, creatures, or objects to which it has a Line of Effect..."

Please feel free to read the entire section; I only posted the parts I felt to be pertinent to this discussion.

Your point was precisely what both sides were ignoring. That's why both sides got upset.

[gbaji]

Section from farther down in the post you quoted:

And the "actual" field under discussion here a cone projected by an eye-thingy's big central eye. Why would anyone's default assumption be that a cone from the eye can penatrate an opaque barrier? Eye's and not going through barriers strikes me as the obvious intuitive way for it to work.

So? This is not a medusa's gaze, where it being able to see you (or you see it) is what makes it work. And what about transparent barriers? I hold up a sheet of glass, and the antimagic field stops there. It has nothing to do with the source being an eye. It's about the nature of the effect in question.

Isn't the Beholder's anti- magic ray an emanation? From the Beholder? (Which is Sunny's creature type, regardless of the lawyers. We'll refer to him as a naive-gaping-floating-orb-with-stalks if necessary).

Already responded to this exact question. I'm not sure how simply repeating the same question, without acknowledging the existence of my response, allows me to do anything other than repeat the same response.

So... Um... It's still an antimagic field. It should behave the same way, regrdless of what is generating it. I guess it's just the game designer in me. I think in terms of "how does this work?", and also "how can I define this in the rules that will create the least confusion and argument?", and yeah, also "how can I construct this so as to avoid easy exploit and abuse?". While we can certainly say that the field vs emanation models have different effects, and both can produce potential for "interesting" use, IMO the field model has less abuse potential *and* is much more clear and concise (and will result in fewer arguments while playing) *and* also makes a lot more sense from a metamagical ponit of view.

I'll also point out (kinda replying to Brian 333's post here), that we previously had a multi-page discussion about the LoS/LoE rules in 3.5 D&D, and the general consensus was that they were poorly writtten and in desperate need of significant GM "interpretation" to make work properly. So I don't find dogmatically clinging to them in order to produce what I also view to be problematic results, is a great way to go.

Again. Not arguing the rules don't technically say "it's an emanation", because they clearly do. I'm just saying that they really should not have been written that way in the first place.

I post one thing and both sides of the argument (even the one I agree with) say I’m wrong, why do I even bother.

Techncially, you didn't actually say anything, nor express an opinion. You merely asked a question.

So. The good news is that no one is saying you are wrong (cause you didn't actually say anything). The bad news is that no one can agree with you either (cause you didn't state a position).

You've taken a bit of "glass half empty" on the whole thing though.

[Quizatzhaderac]

Michael Faraday and Joseph Henry disagree with you.

Below are the sections of the article discussing sable magnetic, then stable electric fields.

For disclosure I should inform you that I just edited page's intro to say that it blocks "some" electromagnetic fields.

Faraday cages cannot block stable or slowly varying magnetic fields, such as the Earth's magnetic field (a compass will still work inside one).

If charge +Q is placed inside an ungrounded Faraday shield ...... So for all intents and purposes, the Faraday shield generates the same static electric field on the outside that it would generate if the metal were simply charged with +Q.

I post one thing and both sides of the argument (even the one I agree with) say I’m wrong, why do I even bother.

An unfortunate consequence of forum conversations is that if you don't have anything contradictory to say, you usually don't say anything.

[Mordar]

Yes. Think in 3 dimensions. V falling means V was offset enough to get hit.


But V fell, which changes the spatial relationship ... in three dimensions.

Do not concur. If a bit of the three dimensional cone (think Dunce Cap) hits you then the magic is suppressed.

Only blocked part of the cone, not all of it.

That's my take.

Sooooooo not my fight, but it is a fun quibble. I could easily agree with the offset (as I indicated in the first place) but I can't get around Page 2 Panels 3 and 4. That much mass eclipsing (timely reference!) V/Sunny suggests to me no room for offset, particularly since Calder isn't holding V off to the side. Add in Bloodfeast and there should only be tiny slivers of anti-magic sneaking through, if any.

Finally, in panels 3 and 4 we see shadows on the wall of our big combatants...but no visible shadow impact on the anti-magic. I put myself about 85/15 (or maybe 80/20) on the "no eclipsing the Sunny" square.

- M

[gbaji]

An unfortunate consequence of forum conversations is that if you don't have anything contradictory to say, you usually don't say anything.

I agree 100% with this statement (see what I did there?)

Sooooooo not my fight, but it is a fun quibble. I could easily agree with the offset (as I indicated in the first place) but I can't get around Page 2 Panels 3 and 4. That much mass eclipsing (timely reference!) V/Sunny suggests to me no room for offset, particularly since Calder isn't holding V off to the side. Add in Bloodfeast and there should only be tiny slivers of anti-magic sneaking through, if any.

Finally, in panels 3 and 4 we see shadows on the wall of our big combatants...but no visible shadow impact on the anti-magic. I put myself about 85/15 (or maybe 80/20) on the "no eclipsing the Sunny" square.

- M

Eh. I'm willing to just chalk that up to the art though. I suppose we could expect Rich to draw the AMF color wash thing with shadows as well, but I'm not going to take the absense of that as having some significant weight in terms of how the magic is actually working. Heck. Having shadows at all is merely an art upgrade in the first place (though... and I'm just realizing the irony as I write this, that did have an actual in world effect on magic/abilities back at the "exploding Inn").

Dunno. To me, it's really just about the inconsistencies created if you apply an AMF as a "flashlight and where the light hits, magic is supressed" effect. Again. I get that's how it's written, but the actual spell description doesn't say that, it's in the general spell rules, which were written not just with AMF in mind, but every single spell effect in the game that has a cone or sperical shape. As I've already stated a couple of times, re-use of code/rules can sometimes results in inconsistent or nonsensical results. And when you encounter such, the correct course of action is to reject the "common rule" and make an exception that better fits the specific case.

I write a fair number of technical docs for my work. A good approach (for sanity if for no other reason) is to modularize the docs. So there's a separate doc/section for each separate "thing you are doing". This makes things easier because you can simply link to the same standard proceedure for something, in a dozen other documents which may include that same proceedure as part of their own larger/longer process. It also means that if the included proceedure changes for some reason, I change it in one doc, and don't have to remember the dozen or so other docs that include it. They all change at the same time. So one big doc could include links to a dozen or more smaller modularized steps/procedures (but possibly different ones, and in different orders, and with different alternative steps included).

But that's also the danger to this. There can be cases where the new/improved procedure works for 11 out of the 12 docs that include it, and I'm not going to know that I've now broken the steps to follow for doing the 12th one. Modularzation can fail when this happens. It's still better than not using it, but it does mean that when some tech follows that one doc, and tries to follow the part inside which references the smaller changed proceedure, and it fails, I'm going to get a call about it, then I'm going to scratch my head, do some investigating and then realize that the minor change we made to account for <other things> actually doesn't work when used in this case.

And that's when I write an exception within the doc (referencing the case in which things should be done differently). Or a new sub-rule, that is used in that case instead of the current one. This happens all the time. There's nothing wrong with it. But it is important to realize when this happens, and be wiling to say "Yeah. That doesn't produce the expected outcome, so we need to change which rule we follow here".

AMFs have existed in D&D since long before 3rd edition D&D codified different spell descriptions, including "burst" and "emanation" and "spread" , and then included those three broad methods into many of the individual spell descriptions. Prior to 3rd edition, I don't recall anyone thinking that AMFs worked in any way other than the way I have described them (anti-magic shell certainly did, and was broadly interpreted that way). So what changed? Did the developers of 3rd edition decide that AMF should work differently than it had worked previously? Or did they modularize their spell descriptions for area effects into three categories, then applied them to the area effect spells in the game, and just didn't think about how this changed how AMF worked?

My money is on the later explanation. I don't think anyone went into the rules writing for 3rd edition thinking "we want to change how AMF works". I'm pretty sure it was just a consequence of how they wrote the rules.


Oh. And for full completenesses sake, the first edition beholder's central eye had an "antimagic ray", which... ironically, I can't actually find a definition for in the rules (it's not a spell in the PHB, or I've somehow missed it like several times looking through). It does appear to be a single target thing though? Honestly been ages since I played 1st edition, much less fought a beholder. For some reason I still always thought it was a cone effect even back then though. May be misremembering.

[Mordar]

Oh. And for full completenesses sake, the first edition beholder's central eye had an "antimagic ray", which... ironically, I can't actually find a definition for in the rules (it's not a spell in the PHB, or I've somehow missed it like several times looking through). It does appear to be a single target thing though? Honestly been ages since I played 1st edition, much less fought a beholder. For some reason I still always thought it was a cone effect even back then though. May be misremembering.

Confirmed there are no descriptors for "anti-magic ray" in the AD&D (1e) MM, PH or DMG. Interestingly, the Eye of the Deep does get a "cone" descriptor added to its central eye...and does say it may be a relative of the Beholder. It also does not appear to have any rules that suggest the cone effect is impeded by objects in the cone itself.

- M

[brian 333]

Below are the sections of the article discussing sable magnetic, then stable electric fields.

For disclosure I should inform you that I just edited page's intro to say that it blocks "some" electromagnetic fields.




An unfortunate consequence of forum conversations is that if you don't have anything contradictory to say, you usually don't say anything.

So, I suppose all those years I spent installing shielded data cables and EMP protection systems were wasted?

Note that I did say that EMF protection is frequency-specific. You design your specific system to protect against specific issues. Most of what I did for EM protection was specific to 60 hz or to broadband, or to prevent induced currents from parallel conductors.

But I can build a special Faraday Cage to protect against varying or intense EM fields. Large ships have them. Look into Degaussing.

[gbaji]

Confirmed there are no descriptors for "anti-magic ray" in the AD&D (1e) MM, PH or DMG. Interestingly, the Eye of the Deep does get a "cone" descriptor added to its central eye...and does say it may be a relative of the Beholder. It also does not appear to have any rules that suggest the cone effect is impeded by objects in the cone itself.

- M

Though, to be fair, the Eye of the Deep's eye is literally a flashlight, so we might actually rule that it does (and it's strange since it uses the label "ray", but then defines a cone effect). The only spell effect I could find that has "ray" in the name is "ray of enfeblement", which is single target. But it seems as though they sometimes used the word ray in the literal meaning "a single line" and sometimes in the common meaning (e.g.: "death ray", which traditionally would be depicted as a cone effect. See "war of the worlds" or "Nicola 'how dare they use my death ray as a weapon of mass destruction!' Tesla" for references.).

It is funny how many terms and concepts the writers for 1st edition would use and just kinda assume that the reader knew what they were talking about (this from the guy making the obscure Sanctuary reference, no less). As an aside, I also looked through the "special spell cases" section of the DMG. The only note for anti-magic shell was that if on another plane, creatures native to that plane would naturally be there, and thus would not be pushed out/away. Which is interesting, but not germain to this conversation.

But yeah. I'm still going with "unintended side effect of the spell terminology consolidation efforts of 3rd edition". Desperately needed spell terminology consolidation, to be sure, but still.

[Quizatzhaderac]

So, I suppose all those years I spent installing shielded data cables and EMP protection systems were wasted?

Protecting against pulses is fine, pulses are different than fields.

Note that I did say that EMF protection is frequency-specific. You design your specific system to protect against specific issues.

The problem is that the word "field" means in the absolutely most general sense of EM interactions.

But I can build a special Faraday Cage to protect against varying or intense EM fields. Large ships have them. Look into Degaussing.

That's a specific type of magnetic field, and has nothing to do with electric fields.

[halfeye]

That's a specific type of magnetic field, and has nothing to do with electric fields.

There are more than one type of electro-magnetic field?

[brian 333]

Protecting against pulses is fine, pulses are different than fields.

The problem is that the word "field" means in the absolutely most general sense of EM interactions.

That's a specific type of magnetic field, and has nothing to do with electric fields.

Current induction is an issue when data and power cables are parallel. The EM Field generated by the current carrying conductors of power cables can induce a current in the data cable conductors. Unless they are shielded. Hmm, what method might we use to accomplish this? Let's ask Dr. Joseph Henry. Likewise, those very long power cables exist within the magnetosphere of the Earth. So, how do we prevent current induction in the power cables which might increase, decrease, or cause fluctuations in the power supplied by those cables? Oh, yeah. Same guy.

Unlike many who used Dr. Henry's experiments for his own inventions, Michael Faraday credited Dr. Henry for his contributions. So did Tesla. Mr. Henry, unfortunately, did not believe in patents, so properties and inventions he described decades before were patented by the likes of Morse, (direct theft of IP,) Bell, (uncredited use of discoveries,) and Edison, (patent everything Henry ever published that had not already been patented so others had to buy the use of Henry's inventions and discoveries from him.)

But current induction, and how to prevent it, were the product of Dr. Henry's work on transformers as refined by Michael Faraday.

And yes, magnetic fields and electromagnetic fields can be canceled by Faraday cages. Not perfectly, but well enough for all practical purposes. My favorite example of this is when lightning strikes an automobile. Most people think the rubber tires are what saves the passengers, but that lightning bolt traveled 100 miles to get there, so why would a six inch gap under the car stop it? It does not. If you could see it happen, and you were at ground level, you'd see hundreds of mini-bolts from the car to the ground. The lightning goes around the shell of the car, and the passengers inside are momentarily surrounded by it. (Unfortunately, that same chassis is part of your car's electrical system, so everything electric will be fried.) The shell of the car is a primitive Faraday Cage, which is why your radio has an external antenna.

The distinctions between Magnetic Fields and Electrical Fields are... Well... Okay, magnetic fields are created by the flow of electrons, and electrons are induced to flow by magnetic fields. Like waves and water. Same thing, except in the very abstract definitions applied to distinguish between them.

[Quizatzhaderac]

There are more than one type of electro-magnetic field?

If we want to say 'the EM field" there's only one, is all of the universe, that covers a bewildering array of interactions.

If we're talking about "a field", then yes, there are an infinite number of possible configurations, but in practice people are usually only talking about a few.

The simplest one is the one around an electric monopole; a simple, stable electric field. This happens when an object has an unequal number of electrons and protons. It is either positive, or negative. When you rub silk and glass together, the silk and glass become electric monopoles. You yourself become an electric monopole for the 15 second or so before you receive a static shock.

The next is an electric dipole, which is two monopoles near each other. One positive end, one negative end.

Next is a magnetic dipole; a stable magnetic field. This is what your refrigerator magnet is. It has a north end and a south end. If you cut it in half, each piece will have a north and south end. It has an equal number of electrons and protons, but more of the electrons and "spinning" in one way that the other.

Sparing you the math, moving positive acts like north, moving north acts like negative, moving negative acts like south, and moving south acts like positive.

Two more complicated ones that are important (and Brian has mentioned it) are wires carrying current. A DC current will have a stable magnetic field but no electric field. It has equal electrons and protons, but the electrons are (on average) going somewhere.

A wire with an AC current will produce a specific type of complex EM field as the electrons are moving in alternating directions. Since the electron movement keeps changing, the magnetic field it produces keeps changing. The changing magnetic field, produces an electric field. This EM field is very good and producing the same current in nearby wires.

Current induction is an issue when data and power cables are parallel. The EM Field generated by the current carrying conductors of power cables can induce a current in the data cable conductors. Unless they are shielded.

Yes, that effect can be shielded against.

If you're just doing conventional electronics, I might be fine with calling that the EM field. But we came to this from the most general direction, asking "what is a field?" by considering "what is a field in physics?", and in physics "the EM" field is the most general thing involving literally every type of electric of magnetic interaction.

And yes, magnetic fields and electromagnetic fields can be canceled by Faraday cages. Not perfectly, but well enough for all practical purposes.

Charge a metal ball, and throw into the cage. Hold a second ball of the opposite change outside the cage, feel it pulled into the cage; the balls on either side of the cage are clearly effecting each other. If you go and determine the pull at every point in space between the two (aka the electric field) and find that it's unaffected by the cage. Do the same with both balls outside the cage but the cage between them and you'll get the same result.

This may be a weird thing to do, but this is quite easy.

Going back to the anti-magic field discussion. In each case that a faraday cage can block an EM field, it's because it forms the exact opposite field. However it can be overwhelmed. In all cases where a faraday cage is practical, the EM source is much smaller than the cage or far away. If you put a radio in a small faraday cage next to a large radio tower, you'll hear the radio.

An antimagic field cannot be overwhelmed by any amount of regular magic, meaning it's much greater than whatever specific aspect of magic it's countering. But "cover" is also overwhelming. The wall's mass overwhelms the arrows mass.

What I find unintuitive about an antimagic field being blocked is that is the random stuff not only interacts with this abstract magic, but overwhelms an overwhelming force.

The distinctions between Magnetic Fields and Electrical Fields are... Well... Okay, magnetic fields are created by the flow of electrons, and electrons are induced to flow by magnetic fields. Like waves and water. Same thing, except in the very abstract definitions applied to distinguish between them.

Electricity is a special case. A very important one, but still special. Both electric and magnetic fields can both exist without moving charges. In fact, they can even exist after the charges no longer do.

[brian 333]

Warping magnetic fields is fun. I encourage everyone to play with multiple magnets and iron filings. Wear gloves if you don't want stained fingertips.

I agree with the above post, but I'd like to mention that you can't negate an EM field, but you can cancel its effects by introducing an opposing field. With the radio in the cage and the powerful transmitter example, the transmission can be prevented from reaching the radio, but it would require the exact opposite field to be generated and the radio receiver to be located where the two fields overlap. A simple Faraday cage can't do that because it requires a steady charge from the origin field to build up an opposing charge on the cage. Fluctuation of the origin EM field is likely to collapse the charge of the induced field.

The same applies to the two magnets, one inside, the other outside the cage. The inside magnet interacts with the cage, builds up an opposing field, then you introduce a third field which either warps or collapses the induced field.

But, there is something else going on. You can try this if you regularly use a cantilever bridge such as the Crescent City Connection. Play an AM radio station as you drive. On your way back, play an FM station. What's the difference? Well, a Faraday cage has to be built for the specific bandwidth and intensity of the field it is expected to counter.

But the specifics of electromagnetic field negation was beyond the scope of my original post about Faraday cages. The point being addressed was that AMF should be treated like an EMF because an EMF can't be blocked. I pointed out that that is exactly what a Faraday cage does. By the logic presented, if an EM Field can be blocked, so can an AMF. You just need something that will block it. It turns out that there are rules that specify what will block an AMF.

[F.Harr]

Sunny! No!

[Precure]

Sunny! Yes!