Final answer:
Capacitor B has a larger capacitance since it holds the same amount of charge at a lower voltage than capacitor A. Capacitance is inversely related to voltage when charge is constant, and is influenced by the area of the plates and distance between them in a parallel plate capacitor.
Step-by-step explanation:
If two capacitors, A and B, hold the same charge but capacitor A is at a higher voltage than capacitor B, then it follows that capacitor B has a larger capacitance. Capacitance is defined by the relationship C = Q/V, where C is the capacitance, Q is the charge, and V is the voltage. Given that both capacitors have the same charge Q, and capacitor A has a higher voltage V than B, then B must have a larger value for C to maintain the equality (since V is in the denominator).
Referring to a parallel plate capacitor, we can further understand this by considering that the capacitance C depends on the area A of the plates and the distance d between them. Larger plate areas and smaller distances increase capacitance because they allow more charge to be stored. In the case of capacitors in parallel, the overall capacitance is the sum of individual capacitors, meaning that if combined into an equivalent single capacitor, the plate area effectively increases, thereby increasing capacitance.