Electric Fields due to a charged disk.

[help1]

Homework Statement

Why is this answer saying that Ea > Eb?

Homework Equations

Everything pertinent to this question is located in this picture:

http://img94.imageshack.us/img94/1187/ch22q9part1.png
[PLAIN]http://img94.imageshack.us/img94/1187/ch22q9part1.png

The question is asking which has the greater magnitude Ea or Eb, and this website says Ea > Eb, just like the solution manual, but that doesn't make sense!

The Attempt at a Solution

I plugged in numbers, and a bigger radius gives a bigger number for Eb, so shouldn't Eb > Ea?

 

[chronos98]

You're right, those don't make sense. Talk to your teacher.

 

[help1]

You're right, those don't make sense. Talk to your teacher.

Any ideas as to where Ec would lie in magnitude?

 

[chronos98]

I'm pretty sure it would be the difference of the two, if c is a donut ring like I think it is. I'll let you figure out how that would compare.

 

[help1]

Seems to me as though the order should be Eb > Ea > Ec instead of Ea > Eb > Ec, as suggested by the text.