Question

Net capacitance of three identical capacitors in series is `1 muF`. What will be their net capacitance in parallel ? Find the ratio of energy stored in two configurations if they are connected to the same source.

Answer 1

Correct Answer - `9 mu F ; 1 ; 9`
Let `C` be the capacity of each of the three condensers.
`:. (1)/(C_(s)) = (1)/(C ) + (1)/(C ) + (1)/(C ) = + (3)/(C )`
or `C_(s) = (C )/(3) = 1 mu F :. C = 3 mu F`
Now, `C_(p) = C + C + C = 3 C = 3xx3 mu F`
`= 9 mu F`
When connected to the same source, `V` is same
`E_(s) = (1)/(2) C_(s) V^(2)` and `E_(p) = (1)/(2) C_(p) V^(2)`
`:. (E_(s))/(E_(p)) = ((1)/(2) C_(s) V^(2))/((1)/(2) C_(p) V^(2)) = (C_(s))/(C_(p)) = (1)/(9)`