Calculating Capacitance to Limit Voltage in Solenoid

In summary, the conversation discusses finding the minimum capacitance needed to prevent a potential difference from rising above 300V when a solenoid with a self-inductance of 2H and carrying a current of 1A has its current source suddenly turned off. The equations used are 1/sqrt(LC) = resonance frequency and LD^2 + I/C = 0 and the energy stored in an inductor is (1/2) L I2.
  • #1
Liquidxlax
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0

Homework Statement



A solenoid with self-inductance L=2H and carrying a steady current of 1 A has the current source suddenly turned off. What is the minimum capacitance that should be connected across the terminals of the solenoid in order to prevent the potential difference generated by collapse of the mag field from rising above 300V.

Homework Equations



1/sqrt(LC) = resonance frequency

LD^2 + I/C = 0


The Attempt at a Solution



Are the capacitor and solenoid in series or parallel and I'm not sure exactly where to start.

Sorry that I don't have any work to show.
 
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  • #2
Connected across the terminals implies that they are in parallel. However, if the solenoid and capacitor are the only remaining components, then one might argue either way:smile:.

You might consider the energy stored in the magnetic field of the solenoid, and what would happen if it were to all be dumped onto the capacitor during the first cycle of oscillation.
 
  • #3
i guess they're are parallel, but I'm not sure how to find the energy stored? Don't i need the time derivative of current?
 

1. How do you calculate the capacitance needed to limit voltage in a solenoid?

The capacitance needed to limit voltage in a solenoid can be calculated using the formula C = Q/V, where C is the capacitance in farads, Q is the charge in coulombs, and V is the maximum voltage that the solenoid can handle.

2. What is the purpose of limiting voltage in a solenoid?

The purpose of limiting voltage in a solenoid is to protect the solenoid and other components in the circuit from damage due to excessive voltage. It also helps to regulate the flow of current and prevent overheating.

3. How does the size of the solenoid affect the required capacitance?

The size of the solenoid does not directly affect the required capacitance. However, a larger solenoid may require a higher capacitance to limit voltage due to the higher potential difference across its larger surface area.

4. Can the capacitance be too high for a solenoid?

Yes, the capacitance can be too high for a solenoid. If the capacitance is too high, it may cause the solenoid to draw too much current and overheat, leading to potential damage.

5. Are there any other factors to consider when calculating capacitance for a solenoid?

Yes, in addition to the maximum voltage and size of the solenoid, other factors to consider when calculating capacitance include the frequency of the electrical signal, the type of dielectric material used, and the desired response time of the solenoid.

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