A) \[9J\]
B) \[\frac{81}{20}J\]
C) \[\frac{9}{25}J\]
D) \[-\frac{9}{4}J\]
Correct Answer: D
Solution :
[d] Work done in displacing charge of 5 \[\mu C\]from B to C is \[W=5\times {{10}^{-6}}({{V}_{C}}-{{V}_{B}})\] \[{{V}_{B}}=9\times {{10}^{9}}\times \frac{100\times {{10}^{-6}}}{0.4}=\frac{9}{4}\times {{10}^{6}}V\] And \[{{V}_{C}}=9\times {{10}^{9}}\times \frac{100\times {{10}^{-6}}}{0.4}=\frac{9}{5}\times {{10}^{6}}V\] So \[W=5\times {{10}^{-6}}\times \left( \frac{9}{5}\times {{10}^{6}}-\frac{9}{4}\times {{10}^{6}} \right)=-\frac{9}{4}J\]You need to login to perform this action.
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