A) 7.8 mJ
B) 4.6 mJ
C) 3.2 mJ
D) 2.5 mJ
Correct Answer: A
Solution :
Initial energy of body of capacitance 4 mF is \[{{U}_{i}}=\frac{1}{2}\times (4\times {{10}^{-6}})\,{{(80)}^{2}}=0.0128J\] Final potential on this body after connection is \[V=\frac{4\times 80+6\times 30}{4+6}=50V.\] So final energy on it \[{{U}_{f}}=\frac{1}{2}\times 4\times {{10}^{-6}}{{(50)}^{2}}=0.005\,J\] Energy lost by this body \[={{U}_{i}}{{U}_{f}}=\text{ 7}.\text{8}mJ\]You need to login to perform this action.
You will be redirected in
3 sec