Final answer:
The voltage to apply for a biphasic defibrillator, provided a 10.0-mA current and 500 ohms resistance, is 5 volts, using Ohm's Law (V = IR). Actual defibrillation for cardiac arrest involves energy delivered in joules, with initial shocks often ranging from 120 to 200 joules.
Step-by-step explanation:
To determine the voltage to apply when using a biphasic defibrillator during open-heart surgery where a 10.0-mA current is needed and the resistance of the path is 500 ohms, Ohm's Law V=IR can be used. This gives us a voltage of (10.0 mA) × (500 Ω) = (10 × 10-3 A) × (500 Ω) = 5 V. Therefore, 5 volts should be applied.
In practice, for actual defibrillation of a patient, the energy delivered is typically measured in joules (J), not volts, and modern biphasic defibrillators often use varied energies depending on the defibrillator's make and model, patient impedance, and clinical circumstances. Typically, initial shocks range from 120 to 200 joules, and for subsequent shocks, energy may be increased if necessary.