Question

Two insulated metallic spheres of capacitance $3\mu F$ and $5\mu F$ are charged to 300 volt and 500 volt. The energy loss when they are connected by a wire is :

• A. $0.37J$
• B. $3.7J$
• C. $0.037J$
• D. $0.73J$

Answer 1

Answer: (C)

$0.037J$

Initial energy of body of capacitance $3\mu F$ is $U_i=1/2\times 5\times {10}^{-6}\times {500}^2=0.625$

Final potential on this body after connection is $V=\frac{3\times 300+5\times 500}{3+5}=425V$

hence final energy on it $U_f=1/2\times 5\times {10}^{-6}{425}^2=0.4515J$

Energy lost by this body$=U_i-U_f=0.0375J$