Final answer:
To raise the power factor of the circuit, an inductor should be placed in series with the elements and the value of the reactance across the inductor can be calculated using a formula.
Step-by-step explanation:
In an AC circuit, the power factor is the amount by which the power delivered in the circuit is less than the theoretical maximum due to the voltage and current being out of phase. A power factor less than 1 indicates that the circuit has reactive power, which can be corrected by adding a reactive component.
In this case, the circuit has a power factor of 0.5 leading, meaning it has capacitive reactance. To raise the power factor to unity (1), an inductor should be placed in series with the elements. The value of the reactance across the inductor can be found using the formula Xl = 1 / (2πfC), where f is the frequency and C is the capacitance.