Question Regarding Capacitance And Inductance

[bobbles22]

Hi there,

I'm doing a home study course including a section on dynamic fields and waves. I am trying to understand how to find capacitance using initial charge, inductance and energy.

From a previous section, I know I can find the maximum current using U_m=1/2 LI²

However, I can't see how to find the capacitance. Can anyone point me in the right direction please.

Many thanks

Bob

 

[berkeman]

Hi there,

I'm doing a home study course including a section on dynamic fields and waves. I am trying to understand how to find capacitance using initial charge, inductance and energy.

From a previous section, I know I can find the maximum current using U_m=1/2 LI²

However, I can't see how to find the capacitance. Can anyone point me in the right direction please.

Many thanks

Bob

What does the circuit look like? Can you upload a PDF?

 

[Baluncore]

Knowing the initial charge and energy should be enough to compute capacitance.

From the definition of capacitance, C = Q / V
therefore V = Q / C.

We know that the energy stored in a capacitor is, E = ½ C V^2

therefore E = ½ C (Q/C)^2
so E = ½ Q^2 / C
hence C = ½ Q^2 / E.

 

[bobbles22]

Its a simple circuit with just a capacitor and a solenoid, nothing else