Question

A few physics questions?

Answer 1

@theEric

Answer 2

I can take a look infrequently! I'd like to help more, but I have lots of studying to do!

Answer 3

Okay! :)

Answer 4

A ferromagnetic material is subjected to strong magnetic field and afterward acts as permanent magnet. Why??
Long-range electric currents circulating iron
Motion of iron nuclei makes magnetic field
Magnetic field aligns magnetic domains mostly in a single direction
Magnetic field gives ferromagnetic material electric charge

I think its C?

Answer 5

Yep!

Answer 6

cool :)
Is it false that magnetic field lines are perpendicular to direction of magnetic field at every point?
I think it is false

Answer 7

It is false!

Answer 8

nice :)
What shape do magnetic field lines have around a wire with a steady current in it?
Lines parallel to direction of wire
spirals converging inward toward wire
concentric circles around wire
none of the above
I think its B?

Answer 9

Nope! They do not converge inward, that I've learned. And you don't see them do so, so they can't be spiraling, either. Do you have another guess?

Answer 10

http://images.search.yahoo.com/search/images;_ylt=A0LEV1kUQGBTBiUAMwlXNyoA?p=magnetic+field+wire&fr=moz35&fr2=piv-web

Answer 11

straight lines radiating outward from wire is actually another option I almost left it out

Answer 12

Nope! Did you check out the link I posted? It's an image search!

Answer 13

oh nvm I think its conecentric circles around the wire :)

Answer 14

Yup! :)

Answer 15

First you need to find the formula for the magnetic field generated by a solenoid!

I have to go!
I'll be back soon.

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/solenoid.html
You double the current. So, what happens to the magnetic field?

Answer 16

Did you find your answer?

Answer 17

You're on the right track!
\(B=\mu nI\)
Next, \(I\) is doubled, and \(\mu\) and \(n\) stay the same. We'll let this new \(I\) be \(I_2\). And let \(B_2\) be the next magnitude of the magnetic field.
So,
\(B_2=\mu nI_2\)
\(I_2\) doubled \(I_1\), so \(I_2=2I_1\). So, really,
\(B_2=\mu n 2I_1\)
So,
\(B_2=2(\mu n I_1)=2B_1\)

Answer 18

These kind of problems come up every once in a while. Like, electrostatic force - what happens when you double the radius?
\(F_1=k\dfrac{q_1\ q_2}{r_1^2}\)
so
\(F_2=k\dfrac{q_1\ q_2}{r_2^2}=k\dfrac{q_1\ q_2}{(2r_1)^2}\\=k\dfrac{q_1\ q_2}{2^2r_1^2}=\dfrac14\left(k\dfrac{q_1\ q_2}{r_1^2}\right)=\dfrac14F_1\)

General method:
Make the substitution of the change you know, and then get the expression to look how it did before.

Answer 19

Well, I guess I didn't finish the last one.
\(B_2=2B_1\), though, so you can substitute your value for \(B_1\) and calculate \(B_2\).

As for the maglev, the wording is weird, but it's definitely not the last two! So I agree!