Solution:
Solution:
Electrostatic energy $$ U=\frac{1}{2}C{{V}^{2}} $$
$$ =\frac{1}{2}(15\times {{10}^{-12}})\times {{(60)}^{2}} $$
$$ =\frac{1}{2}\times 15\times 36\times {{10}^{-12}}\times {{10}^{2}} $$ $$ =270\times {{10}^{-10}} $$
$$ =2.70\times {{10}^{-8}}\,J $$
