Skip to main content
Ch. 25 - Electric Current and Resistance
Giancoli Douglas - Physics for Scientists and Engineers 5th edition
Giancoli Douglas5th editionPhysics for Scientists and EngineersISBN: 9780137488179Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoGiancoli Douglas 5th editionCh. 25 - Electric Current and ResistanceProblema 41
Capitolo 24, Problema 41

(II) A power station delivers 750 kW of power at 12,000 V to a factory through wires with total resistance 3.0 Ω. How much less power is wasted if the electricity is delivered at 50,000 V rather than 12,000 V?

Guida verificata passo dopo passo
1
Step 1: Calculate the current (I) in the circuit when the power is delivered at 12,000 V. Use the formula for power: P=VI, where P is the power (750 kW) and V is the voltage (12,000 V). Rearrange to find I=P/V.
Step 2: Calculate the power wasted in the wires when the voltage is 12,000 V. Use the formula for power loss due to resistance: Ploss=I2R, where I is the current calculated in Step 1 and R is the total resistance of the wires (3.0 Ω).
Step 3: Repeat Step 1 to calculate the current (I) when the power is delivered at 50,000 V. Use the same formula: I=P/V, but substitute 50,000 V for the voltage.
Step 4: Calculate the power wasted in the wires when the voltage is 50,000 V. Again, use the formula Ploss=I2R, but use the current calculated in Step 3.
Step 5: Find the difference in power wasted between the two cases. Subtract the power loss at 50,000 V from the power loss at 12,000 V to determine how much less power is wasted when the electricity is delivered at the higher voltage.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
8m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Power and Voltage Relationship

The relationship between power (P), voltage (V), and current (I) is defined by the equation P = VI. This means that for a given power output, increasing the voltage allows for a decrease in current, which is crucial for minimizing energy losses in transmission lines.
Video consigliato:
Percorso guidato
06:00
Power

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, expressed as V = IR. This principle helps in understanding how resistance affects power loss in electrical systems.
Video consigliato:
Percorso guidato
03:07
Resistance and Ohm's Law

Power Loss in Transmission Lines

Power loss in transmission lines is primarily due to the resistance of the wires, calculated using the formula P_loss = I²R. As current increases, the power lost as heat in the wires also increases, making high-voltage transmission more efficient by reducing current and thus minimizing losses.
Video consigliato:
Percorso guidato
06:00
Power
Pratica correlata
Domanda del libro di testo

You buy a 75-W lightbulb in Europe, where electricity is delivered at 240 V. If you use the bulb in the United States at 120 V (assume its resistance does not change), how bright will it be relative to 75-W 120-V bulbs? [Hint: Assume roughly that brightness is proportional to power consumed.]

1062
views
Domanda del libro di testo

A flashlight uses two AA 1.5-V batteries connected in series to provide 3.0 V across the bulb, as in Fig. 25–4b. The bulb draws 135 mA when turned on.

(a) Calculate the resistance of the bulb and the power dissipated.

(b) By what factor would the power increase if four AA batteries in series (total 6.0 V) were used with the same bulb? (Neglect heating effects of the filament.) Why shouldn’t you try this?

994
views
Domanda del libro di testo

At \$0.12/kWh, what does it cost to leave a 25-W porch light on day and night for a year?

1020
views
Domanda del libro di testo

Calculate the peak current in a 2.5-k Ω resistor connected to a 220-V rms ac source.

965
views
Domanda del libro di testo

Determine the maximum current passing through a 2.7-hp pump connected to a 240-Vrms ac power source.

1570
views
Domanda del libro di testo

A heater coil connected to a 240-Vᵣₘₛ ac line has a resistance of 32Ω. What are the maximum and minimum values of the instantaneous power?

1476
views