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Difficulty: MediumOhm's Law Calculations and Concepts

A technician is testing a direct current (DC) cooling fan motor installed in an equipment rack. When powered by a 48 V48\text{ V} DC supply, the motor draws a steady current of 250 mA250\text{ mA}. What is the electrical resistance of the cooling fan motor in ohms (Ω\Omega)?

Answer: 192 \Omega

Answer

The electrical resistance of the cooling fan motor is 192 Ω192\text{ }\Omega.
According to Ohm's law, resistance is found by dividing voltage by current (R=VIR = \frac{V}{I}). Converting 250 mA250\text{ mA} to 0.25 A0.25\text{ A} and dividing 48 V48\text{ V} by 0.25 A0.25\text{ A} gives exactly 192 Ω192\text{ }\Omega.

Step-by-Step Solution

1
Convert the current from milliamperes to amperes
I=250 mA=0.25 AI = 250\text{ mA} = 0.25\text{ A}
Ohm's law calculations require current to be expressed in the base SI unit of amperes.
2
Calculate resistance using Ohm's law formula (R=VIR = \frac{V}{I})
R=48 V0.25 A=192 ΩR = \frac{48\text{ V}}{0.25\text{ A}} = 192\text{ }\Omega
Dividing the supply voltage by the total circuit current yields the resistance in ohms.

Key Concept

Calculating resistance using Ohm's law (R=VIR = \frac{V}{I}) combined with metric prefix conversion from milliamperes to amperes.
Estimated Time:1m 0s
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Topics

Ohm's Law Calculations and Concepts

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