Potential energy in concentric shells

[TSny]

The answer I got is indeed a correct answer.

Your work looks correct.

 

[SammyS]

The question was "A solid conducting sphere of radius a having a charge Q is surrounded by a conducting shell of inner radius 2a and outer radius 3a as shown.Find the amount of heat produced when switch is closed."
Where is that switch?

The switch makes a connection from the solid sphere to the shell.

 

[ehild]

The switch makes a connection from the solid sphere to the shell.

Have you seen that switch anywhere in the thread, or you could see the original figure in Gracy's book due to your supernatural abilities?

 

[TSny]

Have you seen that switch anywhere in the thread, or you could see the original figure in Gracy's book due to your supernatural abilities?

Had to be the latter.

 

[SammyS]

Have you seen that switch anywhere in the thread, or you could see the original figure in Gracy's book due to your supernatural abilities?

Not supernatural. (Thanks for the vote of confidence, TSny).

Back in Post #47, I suggested to gracy, that she edit the OP. In that suggestion, I added a few words to her restated problem as it appeared in Post #4.

I knew about the switch from a link to a video that gracy sent to me in a pm.

I should have pushed harder for her to give a more complete statement of the problem.
Here is a screen shot:

Here is the figure at a larger scale.

This video can be found on the site: physicsgalaxy.com , by Ashish Arora.