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Course: MCAT > Unit 3

Lesson 1: Foundation 4: Physical and chemical principles

Circuit elements: Cardiac dysrhythmia and defibrillators


Cardiac dysrhythmia, or irregular heartbeat, is a condition that can have a number of causes and manifestations. One example of this is fibrillation, a condition in which the heart erratically contracting due to spontaneous electrical impulses from the cardiac nodes.
A defibrillator is a device that charges up and can deliver a large amount of electrical energy in a short amount of time to someone suffering from cardiac dysrhythmia. This burst of electrical energy has the potential to briefly stop a heart that is beating irregularly. The heart will then immediately restart, and will often revert to a steady, normal beating pace again, as the spontaneous impulses have now been eliminated. One of the main components in a defibrillator is a capacitor.
Figure 1. Defibrillator placement on a patient with cardiac dysrhythmia.
The hospital you work for uses a defibrillator that has a single capacitor with a capacitance of 106 F. When it is about to be used, the defibrillator is charged to a voltage of 4000 V.
How much charge is stored on the defibrillator ‘s capacitor when it has been fully charged?
Choose 1 answer: