A problem involing an LC circuit

[funoras]

Homework Statement

There's an LC circuit that's made of an 31 mH inductor and a planar capacitator. The surface of the plate is 20cm^2 and the distance between the plates is 1 cm. What is the electrical permittivity of the insulator between the plates , if the peak current is 0,2mA and the peak voltage 10V
L=31mH=3.1*10^-2 H
A=20cm^2=2*10^-3 m^2
d=1cm=0,01 m
Imax=0,2mA=2*10^-4 A
Vmax=10V
ε - ?

Homework Equations

C=q/V
C=εA/d

The Attempt at a Solution

 

[berkeman]

Homework Statement

There's an LC circuit that's made of an 31 mH inductor and a planar capacitator. The surface of the plate is 20cm^2 and the distance between the plates is 1 cm. What is the electrical permittivity of the insulator between the plates , if the peak current is 0,2mA and the peak voltage 10V
L=31mH=3.1*10^-2 H
A=20cm^2=2*10^-3 m^2
d=1cm=0,01 m
Imax=0,2mA=2*10^-4 A
Vmax=10V
ε - ?

Homework Equations

C=q/V
C=εA/d

The Attempt at a Solution

Your unit conversions look okay to me.

Now, what equations can you use to relate the peak current in the LC circuit to the peak voltage? When you have peak series current, what is the voltage across the capacitor? When you have peak voltage across the capacitor, what is the current through the inductor?

 

[funoras]

maybe W=LI^2/2 and W=q^2/2C ?

 

[berkeman]

maybe W=LI^2/2 and W=q^2/2C ?

Why do you suggest these two equations? You may be on the right track, but why pick these?

Also, you should double-check the equations you wrote...

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capeng.html

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/indeng.html

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