The resistance of an ammeter is .025 ohm. What is the power reading when it shows 4 amps?

The resistance of an ammeter is .025 ohm. What is the power reading when it shows 4 amps?

• A. 100 milliwatt
• B. 400 milliwatt
• C. 200 milliwatt
• D. 800 milliwatt

Answer: (B)

To find the power reading of the ammeter, we can use the formula for electrical power, which is expressed as \( P = I^2 \cdot R \), where \( P \) is power in watts, \( I \) is the current in amps, and \( R \) is the resistance in ohms. In this case, the resistance of the ammeter is 0.025 ohms, and it shows a current of 4 amps. Plugging these values into the formula gives: \[ P = (4 \, \text{amps})^2 \times 0.025 \, \text{ohms} \] Calculating that step-by-step: 1. \( (4 \, \text{amps})^2 = 16 \, \text{amps}^2 \) 2. \( 16 \, \text{amps}^2 \times 0.025 \, \text{ohms} = 0.4 \, \text{watts} \) Since 1 watt equals 1000 milliwatts, you convert 0.4 watts to milliwatts: \[ 0.4 \, \text{watts}

To find the power reading of the ammeter, we can use the formula for electrical power, which is expressed as ( P = I^2 \cdot R ), where ( P ) is power in watts, ( I ) is the current in amps, and ( R ) is the resistance in ohms.

In this case, the resistance of the ammeter is 0.025 ohms, and it shows a current of 4 amps. Plugging these values into the formula gives:

[

P = (4 , \text{amps})^2 \times 0.025 , \text{ohms}

]

Calculating that step-by-step:

1. ( (4 , \text{amps})^2 = 16 , \text{amps}^2 )

2. ( 16 , \text{amps}^2 \times 0.025 , \text{ohms} = 0.4 , \text{watts} )

Since 1 watt equals 1000 milliwatts, you convert 0.4 watts to milliwatts:

[

0.4 , \text{watts}