Calculating Total Energy Stored in Parallel Capacitors

[BunDa4Th]

Two capacitors, C1 = 25 µF and C2 = 6.0 µF, are connected in parallel and charged with a 150 V power supply.

(a) Calculate the total energy stored in two capacitors.

energy stored = 1/2C(deltaV)^2 or Q^2/2C

I been doing this and its marking me wrong.

first i found both charges which is

Q = VC

C1 = 3750 uC
C2 = 900 uC

then i did

3750^2/2(25) = 281250

900^2/2(6) = 67500

i add both up and get 348750 J

It is saying my answer is incorrect and i did this problem 3 different way getting the same number.

does this look like a system error or is my number really off.

 

[H_man]

Simple error in the units.

You need to take into account that the units of capacitance given are MICRO farads. Do the sums again but this time dividing first by a million before you square the terms.

 

[BunDa4Th]

Thanks for the correction.