# Ur in a room with a magnet and an iron bar how do u know which one is the magnet

#### cragar

ur in a room with 2 iron bars one is a magnet and the other is not , they are the same shape
and size , how do u tell which one is the magnet and all u have is the 2 bars to test this nothing else in the room.

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#### berkeman

Mentor
ur in a room with 2 iron bars one is a magnet and the other is not , they are the same shape
and size , how do u tell which one is the magnet and all u have is the 2 bars to test this nothing else in the room.
Ooo, Ooo, I know, I know.

Is this for homework/coursework, or a Brain Teaser? Do you have an answer you can PM me, so I can allow the thread to continue?

#### cragar

this was asked to my physics class and i was just wondering if someone
could tell me , cause my teacher didn't tell us yet.

#### berkeman

Mentor
this was asked to my physics class and i was just wondering if someone
could tell me , cause my teacher didn't tell us yet.
Well, we're not going to do your classwork for you. I'll move this to the Homework Help forums, and offer you one clue... You need to figure out this homework/coursework yourself (see the "Rules" link at the top of the page).

Hint -- what things can you do with a magnetized iron bar that you cannot do with non-magnetized iron bar?

#### cragar

its not for homework

#### berkeman

Mentor
its not for homework
Your teacher asked you the question, and so far nobody in the class has figured it out. That makes it homework/coursework, as defined by the PF Rules.

My hint didn't help at all?

#### cragar

not really how would u tell which bar pulled which

#### berkeman

Mentor
not really how would u tell which bar pulled which
I didn't say anything about pulling in my hint. Do you have a study group for that class, or some classmates that you can discuss it with? Give my hint to your study group/friends, to see if it sparks a good discussion where you can come up with the answer I have in mind.

#### pallidin

I know the answer, but I assume from this thread that I am not to reveal it.

#### berkeman

Mentor
I know the answer, but I assume from this thread that I am not to reveal it.
Correct, thank you. If you can provide a not-too-obvious hint, though, that is okay. The OP (and his study partners or whatever) really need to do the work on this assignment. It looks like the professor is trying to make them think some

#### cragar

k so where would i move this so some one can answer it.

#### berkeman

Mentor
k so where would i move this so some one can answer it.
We don't do your work for you. This is the PF, and we all (generally) abide by the Rules here, beause they're important.

How would you benefit in the long term if we gave you the answer? In the short term, you would gain a bit in your grade, and in your standing in the class (assuming you lied about how you came up with the answer). In the long term, you would be hurt academically and professionally, because you wouldn't be developing the creative technical thinking skills that your prof is trying to engender with his/her question.

Honestly, the hint that I gave you was a bit too obvious, and I should probably give myself an infraction for giving away a homework question answer. Bounce the hint off of your friends in the class, and turn it into a brainstorming session.

If you rely on others to give you the answer to hard questions in your school work, then I can guarantee that you will fail my interview questions when you try to get a real job with your "hard-earned degree".

C'mon, I practically gave the dang answer away!

#### cragar

would u place the magnets in a T fashion

#### berkeman

Mentor
would u place the magnets in a T fashion
Not what I had in mind, but tell us why you think that might help...

#### cragar

if u place them in T fashion and if there is an attraction the bottom one is the magnet
and if there is no attraction the top one is the magnet because u are in between the poles, what did u have in mind.

#### berkeman

Mentor
if u place them in T fashion and if there is an attraction the bottom one is the magnet
and if there is no attraction the top one is the magnet because u are in between the poles, what did u have in mind.
Hey, that's not bad! I didn't think of that angle -- I'll remember that one.

No, that's not what I had in mind. Bet you get extra credit if you and your study group figure out what I meant by my hint. Even more credit if you give attribution to the PF for the hint (shows academic integrity on your part).

#### berkeman

Mentor
BTW, the "T" solution is more elegant than mine. But when you're faced with a life-or-death McGiver situation, you do what you have to do!

#### cragar

k i still have no clue how u would do it does it have something to do with electricity.

#### berkeman

Mentor
k i still have no clue how u would do it does it have something to do with electricity.
Nope. Per your problem statement, you are in the room with the two bars in your non-conducting pajamas.

Re-post my hint here again, and brainstorm a bit.... You'll figure it out. Talk out loud...

#### cragar

make a compass out of it

#### berkeman

Mentor
make a compass out of it
YES!!! (now be honest, did you think that up, or did your study group do it in group brainstorming? Either way is okay, just get used to being honest about who-all contributed).

But you're not done. There are two decision trees, depending on whether you tried to magnetize with the magnet first or the iron bar first. For full credit (both here and at your school), post how you use this trick not knowing if the bar you swipe over the other is the magnet or not...

(good job!)

#### cragar

so in a way it did haft to do with electricity cause isn't magnetism the movement of eletric charges.

#### berkeman

Mentor
so in a way it did haft to do with electricity cause isn't magnetism the movement of eletric charges.
Not from my perspective.

Quiz Question #2 -- When is magnetism not generated by elecricity?

#### cragar

maybe like when the sun and all its isotopes roatate , or maybe the nuetron magnetic moment. what is the particle of the electro magnetic field.

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