How much voltage is required to move a current of 4.5 amperes through a circuit with a resistance of 4.2 ohms?

To determine the voltage required to move a current through a circuit, Ohm's Law can be applied, which states that voltage (V) is equal to the current (I) multiplied by the resistance (R). The formula is expressed as:

[ V = I \times R ]

In this scenario, the current is given as 4.5 amperes and the resistance is 4.2 ohms. Plugging in these values:

[ V = 4.5 , \text{A} \times 4.2 , \text{Ω} ]

Calculating this gives:

[ V = 18.9 , \text{Volts} ]

This result indicates that to move a current of 4.5 amperes through a resistance of 4.2 ohms, a voltage of 18.9 volts is required, which corresponds accurately to the choice indicated. Thus, this calculation underscores the relationship defined by Ohm's Law, providing a clear rationale for the choice of 18.9 volts as the correct answer.