Max Harge on a Capacitor in LC Circuits

[DODGEVIPER13]

Homework Statement

An oscillating LC circuit consisting of a 1.2 nF capacitor and a 3.3 mH coil has a maximum voltage of 2.6 V.
(a) What is the maximum charge on the capacitor?

Homework Equations

Q=CV

The Attempt at a Solution

I tried Q=CV but this did not work I got the answer 3e-9 when I plugged in but this did not work. I have also tried doing it the long way by solving for energy using .5Li^2 = .5CV^2 then solving for i. Then I solved for w by using ω=1/(√LC) and the solved for the period by using T=2∏/ω which after you find it you can divide by 4 to get time when you can plug in time, angular frequency, and current max to the equation I(max) = -ωQ(max)sin(ωt) this gave me 3e-9 as well which is not correct. The numbers I got for I(max) = .00155692, ω=502518.9076, time=.000003126. Finally I have tried this which I found online Q=(energy of capcitance)V this gave me 1e-8 this did not work either. I double checked the numbers in my calc and they were correct I don't understand!

 

[gneill]

Is it possible that you're being tripped up by required significant figures? Was your charge really 3E-9, or should it be 3.1E-9?

 

[DODGEVIPER13]

I am going to try another calulator mine seems to be off

 

[DODGEVIPER13]

LOL thanks man that worked and I checked it with a new calc.

 

[asteriatic]

It seems like you have made some errors in your calculations. The correct formula to use is Q=CV, where Q is the maximum charge on the capacitor, C is the capacitance (in Farads), and V is the maximum voltage. In this case, the maximum charge on the capacitor would be 1.2 nF * 2.6 V = 3.12 nC. Make sure to double check your units and use the correct values for C and V. Also, remember to convert units if necessary. I hope this helps!