An electronics technician tests a direct current (DC) alarm buzzer with a measured resista… — Armed Services Vocational Aptitude Battery (ASVAB)

An electronics technician tests a direct current (DC) alarm buzzer with a measured resistance of $40\text{ }\Omega$ . If an ammeter connected in the circuit measures a current flow of $0.5\text{ A}$ , what is the voltage applied across the buzzer?

A
$80\text{ V}$
$20\text{ V}$ Answer
C
$0.0125\text{ V}$
D
$20\text{ mV}$

Answer

20\text{ V}

According to Ohm's law, voltage across a component equals the current flowing through it multiplied by its resistance (

V = I \times R

). Multiplying

0.5\text{ A}

40\text{ }\Omega

gives exactly

20\text{ V}

Step-by-Step Solution

Identify the given values and unknown variable from the problem statement.

Current (

I

) =

0.5\text{ A}

, Resistance (

R

) =

40\text{ }\Omega

, Voltage (

V

) = ?

Establishing the known quantities determines which algebraic arrangement of Ohm's law is required.

Select and apply the standard Ohm's law formula for voltage.

V = I \times R

Voltage is equal to the product of current in amperes and resistance in ohms.

Substitute the given numerical values into the formula and calculate.

V = 0.5\text{ A} \times 40\text{ }\Omega = 20\text{ V}

Multiplying the decimal current by the integer resistance yields the total potential difference in volts.

Key Concept

Ohm's Law expresses the fundamental relationship between voltage, current, and resistance in a DC circuit (

V = I \times R

Estimated Time:45s

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