`100` capacitors each having a capacity of `10 muF` are connected in parallel and are charged by a potential difference of `100 kV`. The energy stored in the capacitors and the cost of charging them, if electrical energy costs `108` paise per `kWh`, will be

Options

A. `10^(7)J` and 300 paise
B. `5xx10^(6)J` and 300 paise
C. `5xx10^(6)J` and 150 paise
D. `10^(7)J` and 750 paise

Answer

C

Explanation

Equivalence capacitance of n.
Capacitor in parallel,
`C=nc_(1)=100xx10muF =1000muF=10^(-3)F`
Energy stored, `U=(1)/(2)CV^(2)=(1)/(2)xx10^(-3)xx(10^(5))^(2)`
`=5xx10^(8)J=(5xx10^(6))/(3.6xx10^(6))kWJ`
Net cost `=(5xx10^(6))/(3.6xx10^(6))xx10^(6)="150 paise"`