Energy Stored by Capacitor Video Lessons

Concept

# Problem: In open-heart surgery a small amount of energy will defibrillate the heart.(a) What voltage is applied to the 8.59  μF capacitor of a heart defibrillator that stores 44.8 J of energy? ________KV (b) Find the amount of stored charge. ________mC

###### FREE Expert Solution

(a) Energy stored, U,

$\overline{){\mathbit{U}}{\mathbf{=}}\frac{\mathbf{C}{\mathbf{V}}^{\mathbf{2}}}{\mathbf{2}}}$

U = 44.8 J

C = 8.59 × 10-6 F

$\begin{array}{rcl}\mathbf{V}& \mathbf{=}& \sqrt{\frac{\mathbf{2}\mathbf{U}}{\mathbf{C}}}\\ & \mathbf{=}& \sqrt{\frac{\mathbf{2}\mathbf{×}\mathbf{44}\mathbf{.}\mathbf{8}}{\mathbf{8}\mathbf{.}\mathbf{59}\mathbf{×}{\mathbf{10}}^{\mathbf{-}\mathbf{6}}}}\end{array}$

###### Problem Details

In open-heart surgery a small amount of energy will defibrillate the heart.

(a) What voltage is applied to the 8.59  μF capacitor of a heart defibrillator that stores 44.8 J of energy?

________KV

(b) Find the amount of stored charge.

________mC