Midterm tomorrow, doing practice problems tonight. Can somebody check my answers?

[cirthix]

I've done numbers 11 through 17, but I'm having some trouble with 18.

Could someone please explain 18 and check my answers for the ones I did do?
answers:
http://img440.imageshack.us/img440/7366/answersxi9.jpg
questions:
http://img205.imageshack.us/img205/8265/problemsqy9.jpg

thanks!

edit: it seems that I didn't finish number 17, I only did it for outside of the thick plane. I'll post my answer here shortly for the field within the plane

edit 2: if y<d, E(y)=2yp/e0 in the direction of y(yhat).

 

[dighn]

n/m

 

[cirthix]

title edited.

diagram 2.28 is just a picture of two equally sized, oppisitely charged spheres seperated by a vector of length d.

 

[dighn]

For 1.18, just add up the fields from both spheres using 1.12 part a. The "r" for each sphere would be (the point - center) and if you add it up, you get an equation that depends only on the distance between the centers.

 

[MartyMcFly3]

Its amazing how much you forget once you graduate college and are done with school.

 

[cirthix]

do my other answers look ok?

 

[chuckywang]

Originally posted by: cirthix
title edited.

diagram 2.28 is just a picture of two equally sized, oppisitely charged spheres seperated by a vector of length d.

By symmetry and superpositioning, the E-field inside the overlap should be 0.

EDIT: n/m, that's probably wrong.

 

[cirthix]

Originally posted by: chuckywang

Originally posted by: cirthix
title edited.

diagram 2.28 is just a picture of two equally sized, oppisitely charged spheres seperated by a vector of length d.

By symmetry and superpositioning, the E-field inside the overlap should be 0.

EDIT: n/m, that's probably wrong.

only if d=0

 

[thepd7]

Originally posted by: MartyMcFly3
Its amazing how much you forget once you graduate college and are done with school.

what's truly amazing is how I passed emag without knowing ANY of this. C FTW!

 

[chuckywang]

Originally posted by: cirthix

Originally posted by: chuckywang

Originally posted by: cirthix
title edited.

diagram 2.28 is just a picture of two equally sized, oppisitely charged spheres seperated by a vector of length d.

By symmetry and superpositioning, the E-field inside the overlap should be 0.

EDIT: n/m, that's probably wrong.

only if d=0

Yeah, the right answer is p*d/(3*e_o)

 

[cirthix]

double post

 

[cirthix]

Originally posted by: chuckywang

Originally posted by: cirthix

Originally posted by: chuckywang

Originally posted by: cirthix
title edited.

diagram 2.28 is just a picture of two equally sized, oppisitely charged spheres seperated by a vector of length d.

By symmetry and superpositioning, the E-field inside the overlap should be 0.

EDIT: n/m, that's probably wrong.

only if d=0

Yeah, the right answer is p*d/(3*e_o)

I got that, but note that d is a vector, not a scalar, so it carries the direction of the field as well as scaling it depending on separation.

could you please check my other answers

 

[JohnCU]

i miss emag.

 

[Fenixgoon]

Originally posted by: JohnCU
i miss emag.

i sure as hell don't. E&M is such a PITA.

 

[cirthix]

guys, the answers, are they right or do I need to hit the books more?

 

[cirthix]

 

[hypn0tik]

Errr, never mind. Didn't see the work above. Only saw the last line.

 

[JohnCU]

Originally posted by: Fenixgoon

Originally posted by: JohnCU
i miss emag.

i sure as hell don't. E&M is such a PITA.

even more so when you get into the real world and thing's aren't so easy and simplified. no more infinitely long rods of evenly distributed charge or symmetry.. and what the hell is this noise/EMI stuff that was never mentioned...

 

[JohnCU]

pretty sure 2.11 looks right, i remember doin that one.

 

[JohnCU]

also, you know for most engineering problems, you can just type in the question word for word into google and find HW solutions from 14 other universities that have assigned the same work. that always saved me at 1 in the morning when the exam was at 8.

 

[alkemyst]

Originally posted by: MartyMcFly3
Its amazing how much you forget once you graduate college and are done with school.

What did any of that have to do with becoming a cop?

Probably why it's forgotten.

 

[chuckywang]

Originally posted by: cirthix

Originally posted by: chuckywang

Originally posted by: cirthix

Originally posted by: chuckywang

Originally posted by: cirthix
title edited.

diagram 2.28 is just a picture of two equally sized, oppisitely charged spheres seperated by a vector of length d.

By symmetry and superpositioning, the E-field inside the overlap should be 0.

EDIT: n/m, that's probably wrong.

only if d=0

Yeah, the right answer is p*d/(3*e_o)

I got that, but note that d is a vector, not a scalar, so it carries the direction of the field as well as scaling it depending on separation.

could you please check my other answers

Yeah, but the important thing is that the answer is a constant cause it doesn't depend on r.