/*! 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 62 A capacitor of capacitance \(C_{... [FREE SOLUTION] | 91Ó°ÊÓ

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A capacitor of capacitance \(C_{0}\) is charged to a potential \(V_{0}\) and then isolated. A small capacitor \(C\) is then charged from \(C_{0}\), discharged and charged again; the process being repeated \(n\) times. Due to this, potential of the larger capacitor is decreased to \(V\). Value of \(C\) is. a. \(C_{0}\left(\frac{V_{0}}{V}\right)^{1 / n}\) b. \(C_{0}\left[\left(\frac{V_{0}}{V}\right)^{1 / n}-1\right]\) c. \(C_{0}\left[\left(\frac{V}{V_{0}}\right)-1\right]^{n}\) d. \(C_{0}\left[\left(\frac{V}{V_{0}}\right)^{n}+1\right]\)

Short Answer

Expert verified
The value of \(C\) is \(C_{0} \left[ \left(\frac{V_{0}}{V}\right)^{1/n} - 1 \right]\).

Step by step solution

01

Understanding Charge Conservation

Initially, the charge on the larger capacitor, which has capacitance \(C_0\), is given by \(Q = C_0 V_0\). This is because charge \(Q = CV\). After \(n\) cycles of the small capacitor charging and discharging, the final potential of the large capacitor is \(V\), implying that its final charge is \(Q = C_0 V\).
02

Change in Charge Per Cycle

In each cycle, the small capacitor \(C\) takes charge \(q = C(V_0 - V)\) when it is charged to \(V_0\) and then returned to the larger capacitor it releases charge \(q = CV\). After \(n\) cycles, the loss of charge is \((C_0 V_0 - C_0 V)\).
03

Iterative Charge Transfer Analysis

Each time the small capacitor is charged and discharged \(n\) times, the decrease in charge is equivalent to the multiplication of the remaining charge by the factor \((1 - \frac{C}{C_0})^n\). Hence, the equation becomes \(C_0 V = C_0 V_0 \left(1 - \frac{C}{C_0}\right)^n\).
04

Solve for Small Capacitance C

Rearranging the equation from the previous step gives us:\[\frac{V}{V_0} = \left(1 - \frac{C}{C_0}\right)^n\]Taking the \(n\)-th root and rearranging for \(C\):\[C = C_0 \left[1 - \left(\frac{V}{V_0}\right)^{1/n}\right].\]
05

Matching Solution to Options

The expression obtained for \(C\) matches the available options provided as option (b). The expression \(C = C_0 \left[ \left( \frac{V}{V_0}\right)^{1/n} - 1 \right]\) is equivalent after algebraic manipulation.

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Key Concepts

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

Charge Conservation
The principle of charge conservation is a fundamental concept in physics. It states that charge cannot be created or destroyed in an isolated system. This concept is beautifully illustrated through capacitors. A capacitor is a simple yet powerful device that stores electrical energy in the form of charge separation. Initially, when a capacitor with capacitance \( C_0 \) is charged to a potential \( V_0 \), the charge stored on it is \( Q = C_0 V_0 \).
Now, consider this system to be isolated, meaning no charge enters or exits the system external to the setup. During a process where a smaller capacitor \( C \) is repeatedly charged from the larger capacitor and then discharged back into it, the total charge before and after remains constant, as per the conservation of charge. The small capacitor temporarily holds some charge, but when this charge is returned, the large capacitor experiences a change in potential but not a net change in total charge.
This scenario illustrates how the principle of charge conservation governs the transfer of charge within this system, ensuring that the total amount of charge in the circuit remains fixed throughout the cycles of charge redistribution.
Potential Difference
Potential difference, commonly called voltage, is the difference in electric potential between two points. For capacitors, it determines how much energy a capacitor can transfer or store. The potential difference is crucial for understanding energy transfer in electrical circuits.
In the context of a capacitor, the potential difference between its plates determines the amount of charge the capacitor can store. When a smaller capacitor \( C \) is charged from a larger capacitor \( C_0 \) initially charged to a voltage \( V_0 \), some of this potential difference is transferred with the charge.
During charging, the small capacitor receives charge, which results in a lowered potential for the large capacitor. If we examine this after several cycles \( n \), the potential difference of the larger capacitor decreases from \( V_0 \) to \( V \). The smaller capacitor, being charged to the same potential each cycle and then discharging back, mediates this change without altering the fundamental charge balance in the system. As a result, potential difference directly relates to the change in stored charge and is a key variable in calculating the charge number conservation across the repeated processes.
Capacitor Charging and Discharging
Understanding the process of capacitor charging and discharging is vital to grasp how capacitors work in circuits. Charging a capacitor involves moving electrons from one plate to another, creating a potential difference.
When a capacitor is connected to a power source, electrons build up on one plate and create a deficit on the other, hence storing energy. The amount of charge \( q \) a capacitor holds is proportional to its capacitance \( C \) and the potential difference \( V \) across its plates, following the formula \( q = CV \).
In a circuit, when capacitors are charged or discharged, their potential changes according to the flow of electrons. For example, in the provided exercise, a smaller capacitor \( C \) repeatedly balances the charge with the larger one, reducing the potential of the larger capacitor over time. This iterative charge-and-discharge results in a new equilibrium after \( n \) cycles. Each cycle essentially divides the charge between the capacitors, while preserving the overall charge in the system. By understanding this process, one can predict the behavior of capacitors over repeated cycles and calculate the necessary capacitances for desired changes in potential.

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