# Homework Help: What is the charge that can be stored on this capacitor

1. Jul 17, 2008

### ziplock2k

1. The problem statement, all variables and given/known data

A parallel-plate capacitor has dimensions 3.5cm x 5.2 cm. The plates are separated by a 1.1-mm thickness of paper (dielectric constant k = 3.7). What is the charge that can be stored on this capacitor, when connected to a 1.5-V battery? (E0 = 8.85 x 10^-12 C^2/Nm^2)

2. Relevant equations

C=Keo(A/d)
Qmax=(Cdelta)Vmax

3. The attempt at a solution

C=Keo(A/d)
=3.7(8.85E-12)(18.2E-4/1.1E-3)
=200E-12 F

Qmax=C(deltaVmax)
=(200E-12)(1.5V)
=300E-12 C

300E-12 C does not seem like the right answer

2. Jul 17, 2008

### alphysicist

Hi ziplock2k,

I don't think those numbers give 200e-12 F.

3. Jul 17, 2008

### ziplock2k

C=Keo(A/d)
=3.7(8.85E-12)(18.2E-4/1.1E-3)
=54.18E-12

Qmax=C(deltaVmax)
=(54.18E-12)(1.5V)
=300E-12 C

81.27E-12 C

Is my new calculations right?

4. Jul 17, 2008

### alphysicist

That last number looks right to me.