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Ch 28: Fundamentals of Circuits
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Non è quello che usi tu?Cambia libro di testo
Capitolo 28, Problema 61

What is the current through the 10 Ω resistor in FIGURE P28.61? Is the current from left to right or right to left?
Circuit diagram showing a 12V battery, resistors of 5Ω, 10Ω, and 5Ω, and voltage sources of 3V and 9V.

Guida verificata passo dopo passo
1
Step 1: Analyze the circuit diagram. The circuit consists of three branches, each containing a resistor and a voltage source. The 10 Ω resistor is in the middle branch, and we need to determine the current through it and its direction.
Step 2: Apply Kirchhoff's Voltage Law (KVL) to each loop in the circuit. KVL states that the sum of the voltage drops and rises around any closed loop is zero. Write equations for the top loop, middle loop, and bottom loop.
Step 3: Use Ohm's Law, which states that V = I × R, to express the voltage drops across each resistor in terms of the current through them. For example, the voltage drop across the 10 Ω resistor is 10 × I_10, where I_10 is the current through the 10 Ω resistor.
Step 4: Solve the system of equations obtained from KVL to find the currents in each branch. Pay attention to the direction of the currents based on the polarity of the voltage sources.
Step 5: Determine the direction of the current through the 10 Ω resistor. If the current flows from the positive terminal of the 3 V battery to the negative terminal, it is from left to right. Otherwise, it is from right to left.

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Ohm's Law

Ohm's Law states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points and inversely proportional to the resistance (R) of the conductor. This relationship is expressed mathematically as I = V/R. Understanding this law is essential for calculating the current through resistors in a circuit.
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Resistance and Ohm's Law

Series and Parallel Circuits

In electrical circuits, components can be arranged in series or parallel. In a series circuit, the current is the same through all components, while the total voltage is the sum of the individual voltages. In a parallel circuit, the voltage across each component is the same, and the total current is the sum of the currents through each path. Recognizing the configuration of the resistors is crucial for analyzing the circuit.
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Combining Capacitors in Series & Parallel

Kirchhoff's Voltage Law

Kirchhoff's Voltage Law states that the sum of the electrical potential differences (voltage) around any closed network is zero. This means that the total voltage supplied by sources in a circuit must equal the total voltage drop across the resistors. Applying this law helps in determining the voltage across each resistor and, consequently, the current flowing through them.
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Kirchhoff's Junction Rule
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