/*! 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 73 A capacitor consists of two para... [FREE SOLUTION] | 91Ó°ÊÓ

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A capacitor consists of two parallel plates, each with an area of \(16.0 \mathrm{~cm}^{2},\) separated by a distance of \(0.200 \mathrm{~cm} .\) The material that fills the volume between the plates has a dielectric constant of \(5.00 .\) The plates of the capacitor are connected to a \(300 \mathrm{~V}\) battery. (a) What is the capacitance of the capacitor? (b) What is the charge on either plate? (c) How much energy is stored in the charged capacitor?

Short Answer

Expert verified
(a) Capacitance is 35.4 pF, (b) Charge is 10.62 nC, (c) Energy stored is 1.593 μJ.

Step by step solution

01

Convert units

First, convert the given units to meters to use them in standard formulas. The area is given as \( 16.0 \mathrm{~cm}^2 \). Converting this to square meters:\[A = 16.0 \mathrm{~cm}^2 = 16.0 \times 10^{-4} \mathrm{~m}^2 = 1.6 \times 10^{-3} \mathrm{~m}^2\]The separation is given as \( 0.200 \mathrm{~cm} \). Converting this to meters:\[d = 0.200 \mathrm{~cm} = 0.200 \times 10^{-2} \mathrm{~m} = 2.00 \times 10^{-3} \mathrm{~m}\]
02

Calculate the capacitance

The capacitance \( C \) of a parallel plate capacitor with a dielectric is given by the formula:\[C = \varepsilon_r \varepsilon_0 \frac{A}{d}\]where \( \varepsilon_r = 5.00 \) is the dielectric constant, and \( \varepsilon_0 = 8.85 \times 10^{-12} \mathrm{~F/m}\) is the permittivity of free space.Substituting the values:\[C = 5.00 \times 8.85 \times 10^{-12} \frac{\mathrm{~F}}{\mathrm{~m}} \times \frac{1.6 \times 10^{-3} \mathrm{~m}^2}{2.00 \times 10^{-3} \mathrm{~m}}\]\[C = 35.4 \times 10^{-12} \mathrm{~F} = 35.4 \mathrm{~pF}\]
03

Calculate the charge on the plates

The charge \( Q \) on either plate is given by the formula:\[Q = C \times V\]where \( V = 300 \mathrm{~V}\) is the potential difference. Using the capacitance from Step 2:\[Q = 35.4 \times 10^{-12} \mathrm{~F} \times 300 \mathrm{~V}\]\[Q = 10.62 \times 10^{-9} \mathrm{~C} = 10.62 \mathrm{~nC}\]
04

Calculate the energy stored in the capacitor

The energy \( U \) stored in a capacitor is given by:\[U = \frac{1}{2} C V^2\]Substitute the values for \( C \) and \( V \):\[U = \frac{1}{2} \times 35.4 \times 10^{-12} \mathrm{~F} \times (300 \mathrm{~V})^2\]\[U = \frac{1}{2} \times 35.4 \times 10^{-12} \mathrm{~F} \times 90000 \mathrm{~V}^2\]\[U = 1.593 \times 10^{-6} \mathrm{~J} = 1.593 \mathrm{~μJ}\]

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Key Concepts

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

Dielectric Constant
The dielectric constant, symbolized as \( \varepsilon_r \), is a crucial aspect of capacitors. It represents a material's ability to increase the capacitance of a capacitor compared to one with a vacuum between its plates. When a dielectric material is inserted between the plates, it allows the capacitor to store more charge at the same voltage.

This explains why materials with high dielectric constants are preferred in capacitors used for energy storage. For example, in our problem, the dielectric constant is given as 5.00, which means the material between the plates makes the capacitor five times more effective than if there was a vacuum. By increasing the capacitance, the dielectric material not only allows more charge to be stored but also aids in maintaining a lower voltage across the plates for the same energy storage, enhancing the capacitor's efficiency.
Parallel Plate Capacitor
A parallel plate capacitor consists of two conductive plates separated by a certain distance. The area of the plates and the distance between them are key factors influencing the capacitor's capacitance.

The basic formula for calculating the capacitance \( C \) of a capacitor is \( C = \varepsilon_r \varepsilon_0 \frac{A}{d} \), where \( \varepsilon_r \) is the dielectric constant, \( \varepsilon_0 \) is the permittivity of free space, \( A \) is the area of one plate, and \( d \) is the distance between the plates. For a capacitor with a dielectric, as in our exercise, these parameters directly impact how much electrical charge the device can store.
  • Area (A): Larger plate area increases the capacitance.
  • Distance (d): Greater separation reduces the capacitance.
  • Dielectric Material: Enhances charge storage capability.
Understanding these relationships allows us to predict how a parallel plate capacitor will behave when certain variables are adjusted.
Energy Storage in Capacitors
Capacitors store energy in the electric field established between their plates. This energy can be calculated using the formula \(U = \frac{1}{2} C V^2 \), where \( U \) is the energy stored, \( C \) is the capacitance, and \( V \) is the voltage across the capacitor.

In our solution, with a 300 V battery connected, the energy stored can be determined. The greater the capacitance or voltage, the more energy is stored. A high dielectric constant in the capacitor, as already explained, allows for a larger capacitance, thus increasing the energy storage capacity. Therefore, capacitors with higher dielectric constants store more energy at the same voltage.
  • Capacitance (C): Directly proportional to energy storage.
  • Voltage (V): Larger voltage increases the energy stored exponentially.
By understanding these energy storage aspects, one can appreciate how capacitors can manage power demands in electronic circuits.
Charge Calculation on Capacitors
Determining the charge on a capacitor is vital for understanding how it stores electric energy. The charge \( Q \) on a capacitor is given by \( Q = C \times V \), where \( C \) is the capacitance and \( V \) is the voltage.

In the example problem, the plates are connected to a 300 V battery, and the calculated capacitance is used to find the charge. This formula tells us that for a given voltage, a larger capacitance means more charge can be stored. Efficient charge storage allows capacitors to play critical roles in stabilizing and filtering signals in electronics.
  • Capacitance (C): Higher capacitance results in greater charge storage.
  • Voltage (V): Increasing voltage directly increases the stored charge.
Knowledge of charge calculation helps visualize the capacity and limits of a capacitor in various applications.

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Most popular questions from this chapter

A parallel-plate capacitor is to be constructed by using, as a dielectric, rubber with a dielectric constant of 3.20 and a dielectric strength of \(20.0 \mathrm{MV} / \mathrm{m}\). The capacitor is to have a capacitance of \(1.50 \mathrm{nF}\) and must be able to withstand a maximum potential difference of \(4.00 \mathrm{kV}\). What is the minimum area the plates of this capacitor can have?

DATA A positive point charge \(Q\) is placed at a position \(x_{0}\) on the \(x\) axis. The potential \(V\) is then measured at various points along the \(x\) axis. The resulting data are given in the table: $$ \begin{array}{ll} \hline x \text { position (m) } & \text { Potential }(V) \\ \hline 0 & 90 \\ 0.5 & 45 \\ 1.5 & 23 \\ 2.0 & 18 \\ 2.5 & 15 \\ \hline \end{array} $$ Make a plot of \(1 / V\) as a function of the position. From this plot, determine the position and magnitude of the charge.

Two very large charged parallel metal plates are \(10.0 \mathrm{~cm}\) apart and produce a uniform electric field of \(2.80 \times 10^{6} \mathrm{~N} / \mathrm{C}\) between them. A proton is fired perpendicular to these plates with an initial speed of \(5.20 \mathrm{~km} / \mathrm{s},\) starting at the middle of the negative plate and going toward the positive plate. How much work has the electric field done on this proton by the time it reaches the positive plate?

A uniform electric field has magnitude \(E\) and is directed in the negative \(x\) direction. The potential difference between point \(a\) (at \(x=0.60 \mathrm{~m}\) ) and point \(b\) (at \(x=0.90 \mathrm{~m}\) ) is \(240 \mathrm{~V}\). (a) Which point, \(a\) or \(b\), is at the higher potential? (b) Calculate the value of \(E\). (c) A negative point charge \(q=-0.200 \mu \mathrm{C}\) is moved from \(b\) to \(a\). Calculate the work done on the point charge by the electric field.

Two very large metal parallel plates that are \(25 \mathrm{~cm}\) apart, oriented perpendicular to a sheet of paper, are connected across the terminals of a \(50.0 \mathrm{~V}\) battery. (a) Draw to scale the lines where the equipotential surfaces due to these plates intersect the paper. limit your drawing to the region between the plates, avoiding their edges, and draw the lines for surfaces that are \(10.0 \mathrm{~V}\) apart, starting at the lowpotential plate. (b) These surfaces are separated equally in potential. Are they also separated equally in distance? (c) In words, describe the shape and orientation of the surfaces you just found.

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