Electrostatics Question 105
Question: Two insulated metallic spheres of $ 3\mu F $ and $ 5\mu F $ capacitances are charged to 300 V and 500V respectively. The energy loss, when they are connected by a wire is [CPMT 1999; KCET 2000; Pb. PMT 1999, 2001]
Options:
A) 0.012 J
B) 0.0218 J
C) 0.0375 J
D) 3.75 J
Show Answer
Answer:
Correct Answer: C
Solution:
$ \Delta U=\frac{1}{2}\frac{C _{1}C _{2}{{(V _{2}-V _{1})}^{2}}}{(C _{1}+C _{2})} $
$ =\frac{(3\times 5)\times {{10}^{-12}}\times {{(500-300)}^{2}}}{(3+5)\times {{10}^{-6}}} $
$ =\frac{15\times {{10}^{-12}}\times 4\times 10^{4}}{8\times {{10}^{-6}}}=0.0375J $
