Question

What is the formula for the energy per unit length of a capacitor?

1) E = (1/2) * C * V²
2) E = (1/2) * C * Q²
3) E = (1/2) * Q * V
4) E = (1/2) * Q² / C

Answer 1

The correct formula for the energy stored in a capacitor is E = (1/2) * C * V², which indicates the energy in joules for a capacitor with capacitance C in farads and voltage V in volts.

Step-by-step explanation:

The formula for the energy stored in a capacitor (E) is E = (1/2) * C * V², where C is the capacitance and V is the voltage across the capacitor. This formula represents the energy in joules when the charge (Q) on a capacitor with a voltage V applied is Q = CV. It is important to note that the energy is not simply QV, but QV/2. Using the relationship between charge and capacitance, the energy stored Ecap can be written in various forms:

• E = (1/2) * C * V²
• E = (1/2) * Q² / C
• E = (1/2) * Q * V

Therefore, the correct answer from the given options is E = (1/2) * C * V², which corresponds to the first option provided.