The figure shows a conducting sphere 'A' of radius 'a' which is surrounded by a neutral conducting spherical shell B of radius 'b' (>a). Initially switches S1, S2 and S3 are open and sphere 'A' carries a charge Q. First the switch 'S1' is closed to connect the shell B with the ground and then opened. Now the switch 'S2' is closed so that the sphere 'A' is grounded and then S2 is opened. Finally, the switch 'S3' is closed to connect the spheres together. Find the heat (in Joule) which is produced after closing the switch S3. [Consider b = 4 cm, a = 2 cm and Q = 8 µC]
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When outer surface is grounded charge '–Q' resides on the inner surface of sphere 'B'
Now sphere A is connected to earth potential on its surface becomes zero.
Let the charge on the surface A becomes q
Consider the figure. In this position energy stored
when 'S3' is closed, total charge will appear on the outer surface of shell 'B'. In this position energy stored
Heat produced