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Ch 31: Alternating Current
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoYoung & Freedman Calc 14th EditionCh 31: Alternating CurrentProblema 34a
Capitolo 31, Problema 34a

Off to Europe! You plan to take your hair dryer to Europe, where the electrical outlets put out 240 V instead of the 120 V seen in the United States. The dryer puts out 1600 W at 120 V. What could you do to operate your dryer via the 240 V line in Europe?

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1
Understand the relationship between power, voltage, and resistance. The power (P) of an electrical device is given by the formula: P = V2 / R, where V is the voltage and R is the resistance.
Calculate the resistance of the hair dryer when it operates at 120 V. Use the formula: R = V2 / P. Substitute V = 120 V and P = 1600 W to find R.
Determine the current (I) that the hair dryer draws at 120 V using the formula: I = P / V. Substitute P = 1600 W and V = 120 V to find I.
To operate the dryer at 240 V, you need to ensure that the power remains the same (1600 W). Use the formula: P = V × I to find the new current I at 240 V.
Consider using a step-down transformer or a voltage converter to reduce the 240 V supply to 120 V, allowing the dryer to operate safely without exceeding its designed power rating.

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Voltage

Voltage, measured in volts (V), is the potential difference between two points in an electrical circuit. It drives the flow of electric current, similar to how pressure drives water through pipes. In this scenario, understanding the difference between the 120 V in the US and the 240 V in Europe is crucial for adapting the hair dryer to operate safely and effectively.
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RMS Current and Voltage

Power

Power, measured in watts (W), is the rate at which electrical energy is consumed or converted into other forms of energy. The hair dryer operates at 1600 W, which is the product of voltage and current (P = VI). Knowing the power rating helps determine how the dryer will function under different voltages and what adjustments are necessary to maintain its performance.
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Power

Electrical Resistance

Electrical resistance, measured in ohms (Ω), is the opposition to the flow of electric current. It is related to voltage and current by Ohm's Law (V = IR). When using the dryer in Europe, understanding how resistance affects current flow at different voltages is essential for ensuring the device operates within safe limits and does not overheat or get damaged.
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Electric Flux
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Off to Europe! You plan to take your hair dryer to Europe, where the electrical outlets put out 240 V instead of the 120 V seen in the United States. The dryer puts out 1600 W at 120 V. (b) What current will your dryer draw from a European outlet? (c) What resistance will your dryer appear to have when operated at 240 V?

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