Question

How did they rank the capacitors according to the charge they store?

Answer 1

I understand that $$C_{eq, series} = \Sigma C_n$$ and $$ C_{eq, parallel} = \Sigma (\frac{1}{C_n})^{-1} $$

Answer 2

And I know the charges on capacitors connected in series are the same:
$$ Q_1 = Q_2 = Q_3 = Q_{Tot} $$

Answer 3

And the total potential differences across any number of capacitors connected in series is the sum of the potential differences across each individual capacitor: $$ \Delta V_{tot} = \Delta V_1 + \Delta V_2 + \Delta V_3 $$

Answer 4

I'm just kind of stuck. I don't understand how the charges got ranked in that order.

Answer 5

Because of how the circuit is set up, all the capacitors actually act as one giant capacitor. What this means is that the charge that builds up on Capacitor 1 will equal what builds up on capacitors 2 AND 3 (Conservation of charge). So clearly, Q1 is the largest.

The total charge is split between capacitors 2 and 3, but which is the largest?
\[Q = CV\]
Since the voltage will be the same (they are in parallel), the one with the highest capacitance will have the most charge. So Q3 will be larger than Q2.

Q1 > Q3 > Q2

Answer 6

Awesome! Thank you, I totally get it now.

Answer 7

Happy to help :)