Answer to Question #313130 in Electric Circuits for Ashley

Question

A capacitor is used in a typical flash for a “point-and-shoot” camera. The figure shows a circuit for a camera flash, where a 1.5V cell battery is charging the 2000 μF capacitor. When a flash is required, the energy stored in the capacitor is made to discharge through a discharge tube in0.001 s, giving a powerful flash.

1. If we change the battery into a 5.0V cell, instead of using 1.5V cell, how much energy will be stored in the capacitor?
2. If the flash lasts for about 0.001 s, what is the power delivered by the capacitor during this brief time?

Answer 1

Answer

1.energy stored in capacitor

$U=\frac{CV^2}{2}\\=\frac{2000*10^{-6}*1.5*1.5}{2}\\=2.25*10^{-3}J$

2.

Power

$P=Ut=2.25*10^{-3}*0.001\\=2.25*10^{-6}W$