Electric Fields due to a charged disk.

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

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 doesnt make sense!

The Attempt at a Solution

I plugged in numbers, and a bigger radius gives a bigger number for Eb, so shouldnt Eb > Ea?

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

You're right, those don't make sense. Talk to your teacher.
Any ideas as to where Ec would lie in magnitude?

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.

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