a circuit has a current of 1.2 a. if the voltage decreases to one - third of its original amount while the…

Explanation:

Step1: Recall Ohm's law

$I = \frac{V}{R}$, where $I$ is current, $V$ is voltage and $R$ is resistance. Initially, $I_1=\frac{V_1}{R}$, and $I_1 = 1.2$ A.

Step2: Consider the new - voltage situation

The new voltage $V_2=\frac{1}{3}V_1$, and the resistance $R$ remains the same. The new current $I_2=\frac{V_2}{R}=\frac{\frac{1}{3}V_1}{R}$.

Step3: Express $I_2$ in terms of $I_1$

Since $I_1=\frac{V_1}{R}$, then $I_2=\frac{1}{3}\times\frac{V_1}{R}=\frac{1}{3}I_1$.

Step4: Calculate the new current

Substitute $I_1 = 1.2$ A into the equation for $I_2$. So $I_2=\frac{1}{3}\times1.2$ A $ = 0.4$ A.

Answer:

B. 0.4 A