Electrical power $P$ is given by
$$P = IV$$where $P$ is the electrical power (unit: watt, W),
$I$ is electric current (unit: ampere, A), and
$V$ is the potential difference (unit: volt, V)
The rate of energy converted from electrical energy to other forms as a 2.0 A current passes through a device experiencing a potential difference of 3.0 V is, therefore, 6.0 W or 6.0 J per second.
Substituting the relationship $V = IR$ or $I =\dfrac{V}{R}$ into the equation, we can obtain the alternative equations $$P = I^2R$$ and $$P = \dfrac{V^2}{R}$$ respectively. Any of these 3 equations can be used to calculate electrical power, and the choice on which to use depends or whether current or potential difference gets to be constant.