A typical AAA battery has stored energy of about 3400 J. (Battery capacity is ty

Question

A typical AAA battery has stored energy of about 3400 J. (Battery capacity is typically listed as 625 mA h, meaning that much charge can be delivered at approximately 1.5 V.) Suppose you want to build a parallel plate capacitor to store this amount of energy, using a plate separation of 1.67 mm and with air filling the space between the plates.

a) Assuming that the potential difference across the capacitor is 1.5 V, what must the area of each plate be?

b) Assuming that the potential difference across the capacitor is the maximum that can be applied without dielectric breakdown occurring, what must the area of each plate be?

Explanation / Answer

a)

U = 0.5 C V^2

3400 = 0.5 * C * 1.5*1.5

3022.2 = C

C = kA/d

==> A = dC/k = 2.03e-3*3022.2/1/8.85e-12 = 6.9323e11 m2

b)

3400 = 0.5 * C * 3e6*3e6

7.5556e-10 = C

C = kA/d

==> A = dC/k = 2.03e-3*7.5556e-10/1/8.85e-12 = 0.173 m2

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.