# How much power is produced if a voltage of 7 V is applied to a circuit with a resistance of 42 Omega?

Jun 29, 2018

The power is $= 1.17 W$

#### Explanation:

The power is

$P = U I$

and Ohm's Law is

$U = R I$

$I = \frac{U}{R}$

Therefore,

$P = U \cdot \frac{U}{R} = {U}^{2} / r$

The voltage is $U = 7 V$

The resistance is $R = 42 \Omega$

Therefore,

The power is

$P = \frac{{7}^{2}}{42} = \frac{49}{42} = 1.17 W$

Jun 29, 2018

Approximately $1.17$ watts.

#### Explanation:

Power in here is given by the equation:

$P = {V}^{2} / R$

where:

• $P$ is the power in watts

• $V$ is the voltage in volts

• $R$ is the resistance in ohms

So, we get:

$R = {\left(7 \setminus \text{V}\right)}^{2} / \left(42 \setminus \Omega\right)$

$= \frac{49 \setminus {\text{V}}^{2}}{42 \setminus \Omega}$

$\approx 1.17 \setminus \text{W}$