A 3.00 uF and a 5.00 uF capacitor are connected in series cross a 30.0V battery. A 7.00 uF capacitor is then connected in parallel across the 3.00 uF capacitor.

a)Calculate the equivalent capacitance of the circuit
I think the answer is 3.33 uF.

b)Determine the voltage across the 7.00 uF capacitor.
Im not sure how to do this one. Help please?
Thanks

3 answers

a) correct
b) 10microC in parallel with 5microfarad.

Same q on each, C=Q/V.

Total capacitance= 3.33micro, Q then equals 3.33micro*30v= 99.9E-6 coulombs
So, in the 5micro, then V=q/C=99.9E-6/5E-6=19.99volts

So the remainder voltage is across the 7uf is 10 volts.

Thanks

ulol tanga!