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Three identical resistors are connected in series. When a certain potential difference is applied across the combination, the total power dissipated is \(36 \mathrm{~W}\). What power would be dissipated if the three resistors were connected in parallel across the same potential difference?

Short Answer

Expert verified
108 W would be dissipated in parallel.

Step by step solution

01

Understanding Series Connection

In a series circuit, the total resistance is the sum of individual resistances. If each resistor has a resistance of \( R \), then the total resistance \( R_s \) is \( 3R \). The power dissipated in the series connection is given by \( P_s = \frac{V^2}{R_s} = 36 \mathrm{~W} \).
02

Calculate Resistance of Each Resistor

Using the power formula for series configuration, we have \( P_s = \frac{V^2}{3R} = 36 \). Rearranging gives \( V^2 = 36 imes 3R \), so \( R = \frac{V^2}{108} \).
03

Understanding Parallel Connection

In a parallel circuit, the total resistance \( R_p \) satisfies \( \frac{1}{R_p} = \frac{1}{R} + \frac{1}{R} + \frac{1}{R} = \frac{3}{R} \). Therefore, \( R_p = \frac{R}{3} \).
04

Calculate Power for Parallel Connection

In parallel configuration, the power dissipated \( P_p \) is given by \( \frac{P_p}{V^2} = \frac{1}{R_p} = \frac{3}{R} \). Thus, \( P_p = \frac{3V^2}{R} = 3 \times 36 = 108 \mathrm{~W} \).
05

Concluding the Calculation

For identical resistors, the power dissipated when connected in parallel is 108\( \mathrm{~W} \). This result is due to a reduced total resistance, allowing for greater power dissipation at the same voltage.

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Key Concepts

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

Series and Parallel Circuits
Series and parallel circuits describe two fundamental ways to connect electrical components. In a series circuit, components are connected end-to-end so that the same current flows through each component.
This configuration increases the total resistance since each resistor adds to the overall resistance:
  • Total resistance in series: \( R_s = R_1 + R_2 + R_3 + \ldots \)
In contrast, a parallel circuit is arranged so that each component is connected to the same two points, providing multiple paths for the current. As a result, the voltage across each resistor remains the same.
This setup decreases overall resistance because the current can bypass each resistor:
  • Total resistance in parallel: \( \frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2} + \ldots \)
The difference in resistance distribution affects the current flow and power dissipation, important in calculating electronic device performance and efficiency.
Resistor Networks
Resistor networks consist of multiple resistors interconnected in various configurations to handle specific voltage and current requirements. These networks can combine both series and parallel connections to achieve desired electrical properties.
When designing a resistor network, analyzing the total resistance is crucial:
  • In a series network, the resistances simply sum up, making it straightforward to compute the overall resistance.
  • In a parallel network, the inverse of the total resistance equals the sum of the inverse of each resistor's individual resistance.
This complexity requires careful calculation, especially when networks become more intricate.
Using Ohm's Law, which states \( V = IR \), students can find relationships between voltage, current, and resistance.
A deep understanding of these networks aids in troubleshooting and optimizing electronic circuits, making them essential in electrical engineering.
Electrical Resistance
Electrical resistance is a measure of how much an object opposes the flow of electric current. It is expressed in ohms (\( \Omega \)) and affects how easily current flows through a material.

The resistance of a material depends on several factors:
  • Material type: Metals generally have lower resistance compared to non-metals, which is why they are commonly used in wiring.
  • Length and cross-section: Resistance increases with a longer length and decreases with a larger cross-sectional area.
  • Temperature: For most materials, as temperature increases, resistance also increases.
Ohm's Law, represented as \( V = IR \), describes the relationship between voltage (\( V \)), current (\( I \)), and resistance (\( R \)).
By understanding resistance and its factors, one can predict and control current within circuits, which is crucial for ensuring safe and efficient operation of electrical systems.

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Most popular questions from this chapter

A \(1500-W\) electric heater is plugged into the outlet of a \(120-\mathrm{V}\) circuit that has a \(20-\mathrm{A}\) circuit breaker. You plug an electric hair dryer into the same outlet. The hair dryer has power settings of \(600 \mathrm{~W}, 900 \mathrm{~W}, 1200 \mathrm{~W}\), and \(1500 \mathrm{~W}\). You start with the hair dryer on the \(600-\mathrm{W}\) setting and increase the power setting until the circuit breaker trips. What power setting caused the breaker to trip?

A car battery with a \(12 \mathrm{~V}\) emf and an internal resistance of \(0.04 \Omega\) is being charged wtih a current of \(50 \mathrm{~A}\) (a) Find the potential difference \(V\) across the terminals of the battery. (b) Find the rate at which energy is being dissipated as heat inside the battery. (c) Find the rate of energy conversion from electrical to chemical.

The Wheatstone Bridge. P6.45, called a Wheatstone bridge, is used to determine the value of an unknown resistor \(X\) by comparison with three resistors \(M, N\), and \(P\) whose resistances can be varied. For each setting, the resistance of each resistor is precisely known. With switches \(\mathrm{K}_{1}\) and \(\mathrm{K}_{2}\) closed, these resistors are varied until the current in the galvanometer \(\mathrm{G}\) is zero; the bridge is then said to be balanced. (a) Show that under this condition the unknown resistance is given by \(X=M P / N\). (This method permits very high precision in comparing resistors.) (b) If the galvanometer G shows zero deflection when \(M=850.0 \Omega, N=15.00 \Omega\), and \(P=30 \Omega\), what is the unknown resistance \(X\) ?

Working Late! You are working late in your electronics shop and find that you need various resistors for a project. But alas, all you have is a big box of \(10.0-\Omega\) resistors. Show how you can make each of the following equivalent resistances by a combination of your (d) \(7.5 \Omega\). \(10.0-\Omega\) resistors: (a) \(35 \Omega\), (b) \(1.0 \Omega\), (c) \(3.33 \Omega\),

When a current of \(2 A\) flows in a battery from negative to positive terminal, the p.d. across it is \(12 V\). If a current of \(3 A\) flows in the opposite direction p.d. across the terminals of the battery is \(15 V\). Find the emf of the battery.

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