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Ch 32: AC 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
Tutti i libri di testoKnight Calc 5th EditionCh 32: AC CircuitsProblema 34
Capitolo 32, Problema 34

The heating element of a toaster dissipates 1500 W when connected to a 120 V/60 Hz power line. What is its resistance?

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1
Start by recalling the formula for electrical power dissipation in terms of voltage and resistance: P = V2 / R, where P is the power, V is the voltage, and R is the resistance.
Rearrange the formula to solve for resistance R: R = V2 / P.
Substitute the given values into the formula: V = 120 volts and P = 1500 watts.
Square the voltage: V2 = 120^2.
Divide the squared voltage by the power to find the resistance: R = 120^2 / 1500.

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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. It is mathematically expressed as V = I * R. This relationship is fundamental in electrical circuits and helps in calculating resistance when voltage and current are known.
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Resistance and Ohm's Law

Power in Electrical Circuits

The power (P) dissipated in an electrical circuit is the rate at which energy is used or converted and is calculated using the formula P = V * I, where V is voltage and I is current. In the context of resistive devices like a toaster, power can also be expressed as P = I^2 * R or P = V^2 / R, allowing for the calculation of resistance when power and voltage are known.
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Power in Circuits

Resistance

Resistance (R) is a measure of the opposition to the flow of electric current in a conductor. It is measured in ohms (Ω) and depends on the material, length, and cross-sectional area of the conductor. In the context of the toaster, calculating resistance is essential to understand how efficiently it converts electrical energy into heat, which is crucial for its operation.
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Resistivity & Resistors in Circuits
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