The Flash on a compact camera stores energy in a 120 muF capacitor that is charg

Question

The Flash on a compact camera stores energy in a 120 muF capacitor that is charged to 220 V. When the flash is fired, the capacitor is quickly discharged through a lightbulb with 5.0 oms of resistance.

75. ll The flash on a compact camera stores energy in a 120 peF capacitor that is charged to 220 V. When the flash is fired, the capacitor is quickly discharged through a lightbulb with 5.0 n of resistance a. Light from the flash is essentially finished after two time constants have elapsed. For how long does this flash illuminate the scene? b. At what rate is the bulb dissipating energy 250 us after the flash is fired? c. What total energy is dissipated by the lightbulb?

Explanation / Answer

a)

time constant T = RC = 5*120*10^-6 = 0.6 ms

total time elapsed = 2T = 1.2 ms <<-----answer

------------------

(b)

i = (V/R)*e^-(t/T)

i = (220/5)*e^-(250*10^-6/(0.6*10^-3)) = 29 A

P = i^2*R = 29^2*5 = 4205 W

----------

(c)

total energy U = (1/2)*C*V^2 = (1/2)*120*10^-6*220^2 = 2.904 J

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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