/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 44 In open-heart surgery, a much sm... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

In open-heart surgery, a much smaller amount of energy will defibrillate the heart. (a) What voltage is applied to the \(8.00-\mu \mathrm{F}\) capacitor of a heart defibrillator that stores \(40.0 \mathrm{J}\) of energy? (b) Find the amount of the stored charge.

Short Answer

Expert verified
(a) The applied voltage to the capacitor is approximately \(3169.4 V\). (b) The amount of the stored charge is approximately \(0.0254 C\).

Step by step solution

01

Find the voltage (V)

We can find the voltage using the energy stored in the capacitor (E) and the capacitance (C) using the following equation: \(E = \dfrac{1}{2} C V^2\) Given values: \(E = 40.0 J\) \(C = 8.00 \times 10^{-6} F\) We will solve for V: \(V = \sqrt{\dfrac{2E}{C}}\) Plug in the values and calculate V: \(V = \sqrt{\dfrac{2 \times 40.0}{8.00 \times 10^{-6}}}\) \(V \approx 3169.4 V\) The applied voltage to the capacitor is 3169.4 V.
02

Find the amount of stored charge (Q)

To find the charge stored in the capacitor, we can use the capacitance (C) and the voltage (V) we found in step 1, using the following equation: \(Q = C V\) Given values: \(C = 8.00 \times 10^{-6} F\) \(V = 3169.4 V\) Plug in the values and calculate Q: \(Q = 8.00 \times 10^{-6} \times 3169.4\) \(Q \approx 0.0254 C\) The amount of the stored charge is 0.0254 C.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Capacitor Energy Calculation
Understanding how energy is stored within a heart defibrillator can be essential for grasping the fundamentals of its life-saving operation. At its core lies a device known as a capacitor, which is particular about the amount of energy it can hold. The energy (\(E\)) stored in a capacitor is a result of its capacitance (\(C\)) — a measure of its capacity to store charge — and the voltage (\(V\)) applied to it.

The relationship between the energy stored, the capacitance, and the applied voltage is given by the equation:
\[E = \frac{1}{2} C V^2\]
Breaking down the equation reveals that the energy is directly proportional to both the capacitance and the square of the voltage. This squared relationship with voltage indicates that a small increase in voltage can lead to a substantial increase in stored energy, which is critical in the precise functionality of defibrillators.

In practical applications such as in heart defibrillators, this energy calculation ensures that an optimal amount of energy is delivered to the heart muscle to restore normal rhythm without causing harm. It is important to apply just the right voltage to the capacitor to avoid under or over defibrillation.
Electric Charge Storage
Capacitors are able to store electric charge, which is a fundamental aspect of their operation in devices like defibrillators. The stored charge (\(Q\)) is determined by the product of the capacitance (\(C\)) and the voltage (\(V\)) across the capacitor:
\[Q = C V\]
Capacitance, measured in farads (\(F\)), signifies the amount of electric charge the capacitor can store per unit of voltage. Therefore, a capacitor with a larger capacitance can store more charge at the same voltage.

It's important to note that the charge stored in a capacitor isn't used up like fuel in a car; rather, it can be released in a controlled manner. This is why capacitors are so useful in medical devices such as defibrillators, as they can quickly release the stored charge when needed to deliver a quick and precise electrical shock to the heart to correct abnormal rhythms.
Voltage Calculation in Capacitors
Voltage is the electrical potential difference that is necessary for storing energy in a capacitor. It's essentially the 'push' that drives charge into the capacitor and is critical for the capacitor's operation within a circuit, such as in a heart defibrillator. Determining the voltage required for a specific energy storage (\(E\)) in a capacitor with known capacitance (\(C\)) can be calculated by isolating voltage from the energy formula:
\[V = \sqrt{\frac{2E}{C}}\]
This calculation is crucial in medical applications like defibrillation because applying the correct voltage is imperative for the defibrillator to work effectively. As we learned from the problem provided, voltage is carefully calculated to ensure the defibrillator can store enough energy to restart the heart without causing damage to the heart muscle.

Calculating the right voltage also ensures that the defibrillator's capacitor is not overcharged, which could potentially lead to the capacitor's breakdown and failure of the device at a critical moment. Therefore, understanding how to compute voltage for capacitors is not just an academic exercise but a practical necessity for ensuring the safety and efficacy of life-saving medical equipment.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The value of the capacitance is zero if the plates are not charged. True or false?

Electronic flash units for cameras contain a capacitor for storing the energy used to produce the flash. In one such unit the flash lasts for \(1 / 675\) fraction of a second with an average light power output of \(270 \mathrm{kW}\). (a) If the conversion of electrical energy to light is \(95 \%\) efficient (because the rest of the energy goes to thermal energy), how much energy must be stored in the capacitor for one flash? (b) The capacitor has a potential difference between its plates of 125 V when the stored energy equals the value stored in part (a). What is the capacitance?

Elaborate on why molecules in a dielectric material experience net forces on them in a non-uniform electrical field but not in a uniform field.

Elaborate on the way in which the polar character of water molecules helps to explain water's relatively large dielectric constant.

A spherical capacitor is formed from two concentric spherical conducting shells separated by a vacuum. The inner sphere has radius \(12.5 \mathrm{cm}\) and the outer sphere has radius \(14.8 \mathrm{cm} .\) A potential difference of \(120 \mathrm{V}\) is applied to the capacitor. (a) What is the energy density at \(r=12.6 \mathrm{cm},\) just outside the inner sphere? (b) What is the energy density at \(r=14.7 \mathrm{cm},\) just inside the outer sphere? (c) For the parallel-plate capacitor the energy density is uniform in the region between the plates, except near the edges of the plates. Is this also true for the spherical capacitor?

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.