Chapter 25: Problem 18
If you accidentally leave your car headlights (current 5 A) on for an hour, how much energy drains from the car's \(12-\mathrm{V}\) battery?
Chapter 25: Problem 18
If you accidentally leave your car headlights (current 5 A) on for an hour, how much energy drains from the car's \(12-\mathrm{V}\) battery?
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Get started for freeYour company is overstocked on \(50-\Omega, \frac{1}{2}-\) W resistors. Your project requires \(50-\Omega\) resistors that can be safely connected across a 12-V power source. How many of the available resistors will you need, and how will you connect them?
Three \(1.5-\mathrm{V}\) batteries, with internal resistances \(0.01 \Omega, 0.1 \Omega\) and \(1 \Omega\), each have \(1-\Omega\) resistors connected across their terminals. What's the voltage between each battery's terminals, to three significant figures?
You're designing an external defibrillator that discharges a capacitor through the patient's body, providing a pulse that stops ventricular fibrillation. Specifications call for a capacitor storing 250 J of energy; when discharged through a body with \(40-\Omega\) transthoracic resistance, the capacitor voltage is to drop to half its initial value in \(10 \mathrm{ms}\). Determine the capacitance (to the nearest \(10 \mu \mathrm{F})\) and initial capacitor voltage (to the nearest \(100 \mathrm{V}\) ) that meet these specs.
Show that a battery delivers the most power when the load resistance across its terminals is equal to its internal resistance. (This is not the way to treat a battery, but it's the basis for load matching in amplifiers; see Problem \(65 .\) )
An uncharged \(10-\mu \mathrm{F}\) capacitor and a \(470-\mathrm{k} \Omega\) resistor are in series, and \(250 \mathrm{V}\) is applied across the combination. How long does it take the capacitor voltage to reach \(200 \mathrm{V} ?\)
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