Question

An inductor, a resistor and a capacitor are joined in series with an $AC$ source. As the frequency of the source is slightly increased from a very low value, the reactance

• A. of the inductor increases
• B. of the resistor increases
• C. of the capacitor increases
• D. of the circuit increases

Answer 1

Answer: (A)

of the inductor increases

Reactance in electriacal and electronic systems is the opposition of a circuit element to a change of electric current or voltage.
Ideally a resistor has zero reactance.

Reactance of inductor of inductance $L,X_L=L\omega$. It increases with frequency.

Reactance of capacitor of capacitance $C,X_C=\frac{1}{C\omega }$. It decreases with frequency.

Reactance of circuit $=L\omega -\frac{1}{C\omega }$. It follows a curve both increasing and decreasing when the frequency increases.