Why Does the Voltmeter Read 20V When the Switch is Turned Off in an LC Circuit?

In summary, the conversation discusses the behavior of an inductor and a capacitor in a circuit. It is noted that at t=0, an inductor behaves like an infinite resistance and a capacitor behaves like a pure conductor. This information is used to solve a conceptual problem about the voltage across a voltmeter in a circuit with a switch turned off at t=0.
  • #1
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Hello,

This is just a conceptual question I have for the image below.
http://img22.imageshack.us/img22/7489/44840348.jpg

If the switch is turned off at t=0, why is the voltage across the voltmeter=20V? I understand that current in all inductors is zero. But wouldn't at t=0, current would need to pass through the first resistor, and therefore a voltage has dropped making voltmeter reading less than 20V?

Thank you in advance.
 
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  • #2
First consider a simple LC curcuit. Apply kisrchoff's and solve the differential equation for current. You will get that An inductor behaves like infinite resistance at t=0 and a pure conductor at t=infinity. Form this i think that you would be able to solve the problem

And just for extra information: A capictor behaves like a pure conductor at t=0 and as an infite resistance at t=infinity
 

FAQ: Why Does the Voltmeter Read 20V When the Switch is Turned Off in an LC Circuit?

What is an L-C circuit?

An L-C circuit, also known as a resonant circuit, is a type of electrical circuit that consists of an inductor (L) and a capacitor (C) connected in parallel or in series. It is used to store and transfer energy between the two components at a specific resonant frequency.

What is the purpose of an L-C circuit?

The main purpose of an L-C circuit is to create a resonant frequency, which allows for efficient transfer of energy between the inductor and capacitor. This can be useful in many applications, such as in radio and television receivers, where the resonant frequency is used to select a specific frequency from the incoming signals.

How does an L-C circuit work?

In an L-C circuit, the inductor stores energy in the form of a magnetic field, while the capacitor stores energy in the form of an electric field. When the circuit is closed, the energy oscillates back and forth between the two components, creating a resonant frequency. This oscillation can continue indefinitely as long as there is no resistance in the circuit.

What factors affect the resonant frequency of an L-C circuit?

The resonant frequency of an L-C circuit is affected by the values of the inductance and capacitance, as well as the resistance in the circuit. The higher the inductance and capacitance values, the lower the resonant frequency will be. The resistance in the circuit can also affect the resonant frequency by dampening the oscillations.

How are L-C circuits used in real-world applications?

L-C circuits are commonly used in various electronic devices, such as radios, televisions, and computers. They are also used in electrical transmission systems to regulate power flow and in wireless charging systems to transfer energy wirelessly. Additionally, L-C circuits are used in research and scientific experiments to study the properties of resonance and frequency.

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