Final answer:
The correct answer is that when two very large sheets are separated by a distance 'd', the capacitance decreases. This is because capacitance is inversely proportional to the distance between the plates, so increasing the distance weakens the electric field and reduces the ability to store charge. Option A is the correct answer.
Step-by-step explanation:
When considering a system of two parallel plate capacitors, the distance between the capacitor plates is a key factor in determining the capacitance of the system. Capacitance is the ability to store an electric charge, and in the case of parallel plates, it is inversely proportional to the distance between the plates. When you separate the plates further apart (increasing the distance 'd'), the capacitance decreases because the electric field strength between the plates weakens. Since the electric field is what maintains the separation of charges on the plates, reducing its strength makes it harder to store charges at a given voltage, thereby decreasing capacitance.
Contrary to some misconceptions, capacitance is in fact inversely proportional to the distance between the capacitor plates. If the voltage across the plates is held constant and the distance between the plates is increased, the capacitance will decrease. However, the potential energy stored in the capacitor might increase because potential energy in a capacitor is given by ½ CV2. Since the capacitance C is decreasing and the voltage V remains the same, the overall effect on energy would depend on the relative change in capacitance.
The correct option for what happens when two very large sheets are separated by a distance 'd' is that the capacitance decreases (Option A). This conceptual understanding is crucial in fields such as circuit design and electrical engineering.