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Three resistors having resistances of \(1.60 \Omega, 2.40 \Omega,\) and 4.80\(\Omega\) are con0nected in parallel to a \(28.0-\mathrm{V}\) battery that has negligible internal resistance. Find (a) the equivalent resistance of the combination; (b) the current in each

Short Answer

Expert verified
Equivalent resistance is 0.80 Ω; Currents are 17.5 A, 11.67 A, and 5.83 A.

Step by step solution

01

Identify the Formula for Parallel Resistance

When resistors are connected in parallel, the reciprocal of the equivalent resistance \( R_{eq} \) is the sum of the reciprocals of each resistor's resistance. The formula is \( \frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} \).
02

Calculate Reciprocal of Equivalent Resistance

Substitute the given resistances into the formula: \( \frac{1}{R_{eq}} = \frac{1}{1.60} + \frac{1}{2.40} + \frac{1}{4.80} \). This calculates to \( 0.625 + 0.4167 + 0.2083 = 1.25 \).
03

Find the Equivalent Resistance

Take the reciprocal of the sum from the previous step to find \( R_{eq} \): \( R_{eq} = \frac{1}{1.25} = 0.80 \, \Omega \).
04

Identify the Formula for Current in Each Resistor

Use Ohm’s Law \( I = \frac{V}{R} \) to find the current through each resistor. The total voltage \( V \) is 28.0 V.
05

Calculate Current Through 1.60 Ω Resistor

Apply Ohm’s Law for the first resistor: \( I_1 = \frac{28.0}{1.60} = 17.5 \, \text{A} \).
06

Calculate Current Through 2.40 Ω Resistor

Apply Ohm’s Law for the second resistor: \( I_2 = \frac{28.0}{2.40} = 11.67 \, \text{A} \).
07

Calculate Current Through 4.80 Ω Resistor

Apply Ohm’s Law for the third resistor: \( I_3 = \frac{28.0}{4.80} = 5.83 \, \text{A} \).

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Key Concepts

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

Ohm's Law
Ohm's Law is a fundamental principle in electronics and electrical engineering. It relates the voltage, current, and resistance in a circuit. The law is typically expressed with the formula: \[ I = \frac{V}{R} \]Here,
  • I stands for the electric current (measured in amperes),
  • V represents the potential difference or voltage (measured in volts),
  • R is the resistance (measured in ohms).
Ohm's Law helps us predict how much current will flow through a component when a certain voltage is applied across it. In parallel circuits, like the one we're discussing, each resistor gets the full voltage from the power source. Thus, to find the current through each resistor, you simply divide the circuit's voltage by the individual resistance of that resistor. This straightforward application makes it easy to solve for unknowns in simple circuits.
Current Calculation
Calculating the current involves using Ohm’s Law, where the current through each resistor in a parallel circuit is determined separately. Because all resistors share the same voltage in parallel circuits, the calculation is straightforward. For each resistor:
  • The current through the 1.60 Ω resistor is calculated as \( I_1 = \frac{28.0}{1.60} \approx 17.5 \text{ A} \).
  • The current through the 2.40 Ω resistor is \( I_2 = \frac{28.0}{2.40} \approx 11.67 \text{ A} \).
  • The current through the 4.80 Ω resistor is \( I_3 = \frac{28.0}{4.80} \approx 5.83 \text{ A} \).
As you can see, each calculation uses the formula from Ohm's Law, which makes it easy to figure out the current when you know the resistance and voltage. This method ensures you understand each component's contribution to the total circuit behavior.
Resistor Networks
Resistor networks can be simple or complex arrays of resistors connected in series, parallel, or a combination of both. In a parallel circuit, each resistor is connected directly across the power source, which means they all experience the same voltage. The conceptual beauty of parallel circuits lies in the additive nature of conductiveness. To find the equivalent resistance, you sum the reciprocals of all individual resistances:\[\frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}\]In this exercise, using the formula, you find the value:\[R_{eq} = \frac{1}{1.25} = 0.80\, \Omega \]This simplified method helps manage complex networks by reducing them to single equivalent resistors, making calculations easier. Understanding these principles is crucial for analyzing real-world electrical systems and creating efficient circuit designs.

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Most popular questions from this chapter

A resistor and a capacitor areconnected in series to an emf source. The time constant for the circuit is 0.870 \(\mathrm{s}\) . (a) A second capacitor, identical to the first, is added in series. What is the time constant for this new circuit? (b) In the original circuit a second capacitor, identical to the first, is con- nected in parallel with the first capacitor. What is the time constant for this new circuit?

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A. \(2.36-\mu F\) capacitor that is initially uncharged is connected in series with a \(4.26-\Omega\) resistor and an emf source with \(\mathcal{E}=120 \mathrm{V}\) and negligible intermal resistance. (a) Just after the connection is made, what are (i) the rate at which electrical energy is being dissipated in the resistor; (ii) the rate at which the electrical energy stored in the capacitor is increasing; (iii) the electrical energy stored in the capacitor is increasing; (iii) the electrical power output of the source? How do the answers to parts (i), (ii), and (iii) compare? (b) Answer the same questions as in part (a) at a long time after the connection is made. (c) Answer the same questions as in part (a) at the instant when the charge on the capacitor is one-half its final value.

A resistor with \(R=850 \Omega\) is connected to the plates of a charged capacitor with capacitance \(C=4.62 \mu F\) . Just before the connection is made. the charge on the capacitor is 8.10 \(\mathrm{mC}\) .connection is made, the charge on the capacitor is 8.10 \(\mathrm{mC}\) . (a) What is the energy initially stored in the capacitor? (b) What is the electrical power dissipated in the resistor just after the connec- tion is made? (c) What is the electrical power dissipated in the resistor at the instant when the energy stored in the capacitor has decreased to half the value calculated in part (a)?

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