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Zorluk: OrtaElectricity and Magnetism

A workshop exhaust fan is connected to a 120 V120\text{ V} power supply and consumes 480 W480\text{ W} of electric power during normal operation. What is the effective electrical resistance of the fan motor, in ohms (Ω\Omega)?

Cevap: 30 ohms

Cevap

The effective electrical resistance of the fan motor is 30 Ω30\,\Omega.
To find the resistance from voltage and power, determine the current using I=PV=480 W120 V=4 AI = \frac{P}{V} = \frac{480\text{ W}}{120\text{ V}} = 4\text{ A}, then use Ohm's law R=VI=120 V4 A=30 ΩR = \frac{V}{I} = \frac{120\text{ V}}{4\text{ A}} = 30\,\Omega. Alternatively, using R=V2PR = \frac{V^2}{P} yields 1202480=14400480=30 Ω\frac{120^2}{480} = \frac{14400}{480} = 30\,\Omega.

Adım Adım Çözüm

1
Calculate the electric current flowing through the fan motor using the electrical power formula P=V×IP = V \times I.
I=PV=480 W120 V=4 AI = \frac{P}{V} = \frac{480\text{ W}}{120\text{ V}} = 4\text{ A}
Electric power equals the product of voltage and current, so dividing total wattage by applied voltage determines circuit current.
2
Calculate the resistance using Ohm's law rearranged as R=VIR = \frac{V}{I}.
R=120 V4 A=30 ΩR = \frac{120\text{ V}}{4\text{ A}} = 30\,\Omega
Resistance represents the opposition to current flow and is found by dividing the applied voltage by the circuit current.

Anahtar Kavram

Relationship between electrical power (P=IVP = IV) and Ohm's law (V=IRV = IR)
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