Problem — current and power on a resistor

Problem

A resistor of $18\ \Omega$ is connected to a $9{,}0\ \text{V}$ battery. Calculate the current and the power dissipated.

Solution

Current from Ohm’s law: $I = \frac{V}{R} = \frac{9{,}0\ \text{V}}{18\ \Omega} = 0{,}50\ \text{A}$

Power dissipated: $P = V\,I = 9{,}0\ \text{V} \cdot 0{,}50\ \text{A} = 4{,}5\ \text{W}$ (equivalent to $P = V^2/R = 81/18 = 4{,}5\ \text{W}$).

$\ev{I = 0{,}50\ \text{A} \qquad P = 4{,}5\ \text{W}}$

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Topics: Circuiti elettrici Concepts: Legge di Ohm · Potenza