Plusivo DM401B - Joules Law for Electrical Power; Example

8.2 Joule's Law for Electrical Power
Electric power is the rate of the emitting power from a resistor per unit time, the unit of power is
watt.
𝑃 = 𝐼 · 𝑉
𝑃 = 𝐼
2
· 𝑅
𝑃 =
𝑉
2
𝑅
P is the power on the resistor.
I is the current through the resistor.
V is the voltage around the resistor.
R is the resistance.
Note: There are many types of emitting power, it may be a rotary power, light, heat, etc.
8.2.1 Example
Calculate the power on the resistor.
To calculate the power on the resistor, we need any two values of these: Voltage, Current or
Resistance.
In our example, we have the voltage and the resistance, so we can use this formula:
𝑃 =
𝑉
2
𝑅
(3 𝑉)
2
510 Ω
= 0. 0176 𝑊 = 17. 6 𝑚𝑊
Let us see what we will get if we built this circuit in reality and calculate the power using the
multimeter.
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Mastering the Art of Measurement (DM401B Smart Digital Multimeter) r.01 www.plusivo.com