Question

When a capacitor is connected in series LR circuit, the alternating current flowing in the circuit}

• A. remains constant
• B. increases
• C. decreases
• D. is zero

Hint:

Current is maximum at resonance ($X_L = X_C$).

Answer 1

The Correct Option is B

Step 1: Concept
In a series LR circuit, impedance $Z_{LR} = \sqrt{R^2 + X_L^2}$.
Step 2: Analysis
When a capacitor is added (LCR circuit), $Z_{LCR} = \sqrt{R^2 + (X_L - X_C)^2}$.
Step 3: Logic
The term $(X_L - X_C)^2$ is less than $X_L^2$ (assuming typical values before resonance). The capacitive reactance opposes the inductive reactance, reducing the total net reactance and thus reducing impedance $Z$.
Step 4: Conclusion
Since $I = V/Z$, a decrease in impedance $Z$ leads to an increase in current $I$.
Final Answer: (B)