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

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}