Why does voltage differ in combination of capacitors?

The positive plates and negative plates of each capacitor originate from the same place. Which means, the potential difference across both pairs of plates, is the same. Now, remember that Voltage is what pulls the charges onto the plates. read more

So, they have different potentials. Voltage across the plates, is just potential difference between those points. That's why the voltage across them is different. (Besides, if voltage weren't different in series, there would be no current flow). Now, consider charge. Positive plate of C2 and negative plate of C1 are connected. read more

It is impossible to predict the voltage on each capacitor when they are connected in series. The current is the same in the circuit but the voltage on each capacitor depends on the entire history of the current and charge of each capacitor. read more

The total charge , however, stored in the two capacitors is divided between the capacitors, since it must distribute itself such that the voltage across the two is the same. Since the capacitors may have different capacitances, and , the charges and may also be different. read more