Is the Energy Stored in a Capacitor Really QV Instead of QV/2?

  • Thread starter Clara Chung
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    Capacitor
In summary, the correct energy supplied by the voltage source is 0.288mJ, while the printed model answer of 0.576mJ may have been a mistake due to confusion between QV and QV/2.
  • #1
Clara Chung
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Homework Statement
Attached below. I want to check whether my answer is right because the model answer is 0.576 mJ. Thank you.
Relevant Equations
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  • #2
0.288 millijoules looks right.
 
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  • #3
Yes, 0.288mJ looks correct.
But the energy supplied by the voltage source is 0.576mJ, and maybe that's what they printed as the model answer by mistake.
 
  • #4
cnh1995 said:
Yes, 0.288mJ looks correct.
But the energy supplied by the voltage source is 0.576mJ, and maybe that's what they printed as the model answer by mistake.
cnh1995: I agree that 0.288mJ looks correct. But I have not been able to see how to support your statement that "the energy supplied by the voltage source is 0.576mJ". Assuming you are correct, is it possible to interpret the assigned calculation to mean the energy supplied by the voltage source?
 
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  • #5
sojsail said:
But I have not been able to see how to support your statement that "the energy supplied by the voltage source is 0.576mJ".
Well, it can be shown mathematically, but I don't think this problem requires that. :smile:
I mentioned it because I thought perhaps the given wrong answer key had something to do with it.
 
  • #6
Maybe they mistakenly took the energy to be QV instead of QV/2?
 
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Related to Is the Energy Stored in a Capacitor Really QV Instead of QV/2?

1. What is a capacitor?

A capacitor is an electronic component that stores electrical energy in the form of an electric field. It consists of two conductive plates separated by an insulating material called a dielectric.

2. How does a capacitor work?

When a voltage is applied across the plates of a capacitor, one plate accumulates a positive charge and the other accumulates a negative charge. This creates an electric field between the plates, allowing the capacitor to store energy.

3. What is the purpose of a capacitor in a circuit?

Capacitors are used in circuits to store electrical energy, filter out unwanted signals, and provide a temporary power source. They can also be used to control the flow of current within a circuit.

4. How do you calculate the capacitance of a capacitor?

The capacitance of a capacitor is calculated by dividing the charge on one plate by the potential difference between the two plates. It can also be determined by the size and spacing of the plates, as well as the type of dielectric used.

5. What are the different types of capacitors?

There are several types of capacitors, including ceramic, electrolytic, film, and variable capacitors. Each type has its own unique properties and is used for different purposes in electronic circuits.

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