How Do You Calculate Charge and Current Change Rate in LC Circuits?

[dwn]

I'm having a difficult time finding any information in regards to LC circuits.

The total energy in an circuit is 5.0*10^-6 J. If C= 15 microfarads, what is the charge
on the capacitor? the ans is 12 microC

An circuit has an inductance of 15 mH and a capacitance of 10 µF. At one instant
the charge on the capacitor is 25 µC. At that instant the current is changing at what rate?

ans : 170 A/s

Again, I am unable to find the formula/information to solve these equations. Can someone please tell me what I am missing. I know the inductance equations (RLC) , but I don't see any in our book that contain just LC.

Thank you.

 

[berkeman]

I'm having a difficult time finding any information in regards to LC circuits.

The total energy in an circuit is 5.0*10^-6 J. If C= 15 microfarads, what is the charge
on the capacitor? the ans is 12 microC

What is the equation for the energy stored on a capacitor in terms of the capacitance and voltage?

An circuit has an inductance of 15 mH and a capacitance of 10 µF. At one instant
the charge on the capacitor is 25 µC. At that instant the current is changing at what rate?

ans : 170 A/s

Again, I am unable to find the formula/information to solve these equations. Can someone please tell me what I am missing. I know the inductance equations (RLC) , but I don't see any in our book that contain just LC.

Thank you.

Write the differential equations for a series LC circuit. Does that help you to get to the answer?