Defibrillator

Definition

A defibrillator is a medical device that delivers a dose of electric current (often called a counter-shock) to the heart to restore a normal heartbeat. It utilizes stored energy in capacitors to generate and deliver this high-voltage shock.

5 Must Know Facts For Your Next Test

1. Defibrillators store energy in capacitors until it is discharged as an electric shock.
2. The amount of energy stored in a capacitor is given by $U = \frac{1}{2}CV^2$, where $U$ is the stored energy, $C$ is the capacitance, and $V$ is the voltage.
3. Capacitors used in defibrillators can charge up to several thousand volts.
4. The electric field generated by a charged capacitor can be calculated using the formula $E = \frac{V}{d}$, where $E$ is the electric field strength, $V$ is the voltage, and $d$ is the distance between capacitor plates.
5. Defibrillators use both monophasic (single-direction current) and biphasic (alternating direction current) waveforms.

Review Questions

• What formula represents the energy stored in a capacitor used in defibrillators?
• How does increasing voltage affect the energy stored in a capacitor?
• What are the differences between monophasic and biphasic waveforms in defibrillators?

Related terms

Capacitance: The ability of a system to store an electric charge per unit voltage; measured in farads (F).

Electric Field: A field around charged particles that exerts force on other charged objects; calculated as $E = \frac{V}{d}$.

Voltage: The difference in electric potential between two points; measured in volts (V).