# Simple question about capacitor

Clara Chung
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:
Attached below

#### Attachments

• 1554028557952.png
40.7 KB · Views: 300

## Answers and Replies

Asymptotic
0.288 millijoules looks right.

Clara Chung
Homework Helper
Gold Member
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.

sojsail
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?

Last edited:
Homework Helper
Gold Member
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.
I mentioned it because I thought perhaps the given wrong answer key had something to do with it.

Mentor
Maybe they mistakenly took the energy to be QV instead of QV/2?

cnh1995