An avionics technician tests a 72\text{ V} direct current (DC) instrument circuit. If the … — Armed Services Vocational Aptitude Battery (ASVAB)

An avionics technician tests a $72\text{ V}$ direct current (DC) instrument circuit. If the circuit's total resistance is measured at $1.2\text{ k}\Omega$ , what is the current flowing through the circuit?

A
$16.7\text{ mA}$
$60\text{ mA}$ Answer
C
$60\text{ A}$
D
$86.4\text{ A}$

Answer

60\text{ mA}

According to Ohm's law, current equals voltage divided by resistance (

I = V / R

). Converting

1.2\text{ k}\Omega

to base units gives

1200\text{ }\Omega

. Dividing

72\text{ V}

1200\text{ }\Omega

produces

0.06\text{ A}

, which is equivalent to

60\text{ mA}

Step-by-Step Solution

Convert the given resistance from kilo-ohms to base ohms

R = 1.2\text{ k}\Omega = 1.2 \times 10^3\text{ }\Omega = 1200\text{ }\Omega

Standard electrical calculations using Ohm's law require values to be expressed in SI base units (volts, amperes, and ohms).

Apply Ohm's law formula to solve for current (

I

)

I = \frac{V}{R} = \frac{72\text{ V}}{1200\text{ }\Omega} = 0.06\text{ A}

Current is directly proportional to voltage and inversely proportional to resistance.

Convert the current from amperes to milliamperes

I = 0.06\text{ A} \times 1000\text{ mA/A} = 60\text{ mA}

Expressing the small current value in milliamperes matches standard electronic measurement conventions.

Key Concept

Ohm's Law Current Calculation (

I = \frac{V}{R}

) with Metric Prefix Conversion

Alternative Method

Convert the calculation directly using milliamperes:

1\text{ V} / 1\text{ k}\Omega = 1\text{ mA}

. Therefore,

72\text{ V} / 1.2\text{ k}\Omega = 60\text{ mA}

Estimated Time:1m 0s

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Answer

Step-by-Step Solution

Key Concept

Common Mistakes

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