In RL series circuit. which quantity is lagging

Question

Examoogle · Accepted Answer

Option A: Current

Explanation & Concepts:
In an RL series circuit, the current lags behind the applied voltage due to the inductive property of the coil. The inductance opposes any change in current, resulting in a phase difference where the current reaches its peak value after the voltage.

Working Principle: When an AC voltage is applied to an inductor, it generates a back electromotive force (EMF) according to Faraday's Law, $e = -L \frac{di}{dt}$. This back EMF opposes the flow of current. Consequently, the current is delayed by an angle $\phi$ relative to the supply voltage, where $	an(\phi) = \frac{X_L}{R}$.

Key Formulas: $Z = \sqrt{R^2 + X_L^2}$ — Total impedance of the series RL circuit; $\phi = \arctan\left(\frac{\omega L}{R}ight)$ — Phase angle by which current lags voltage

Key Points: The inductive reactance $X_L = 2\pi f L$ increases with frequency.; The power factor of an RL circuit is always lagging.; The voltage across the resistor is in phase with the current, while the voltage across the inductor leads the current by $90^\circ$.

Advantages: Acts as a natural low-pass filter in signal processing.; Limits inrush current in power systems and electronic starters.

Disadvantages: Introduces phase distortion in communication signals.; Requires reactive power which can lower the overall power factor of a distribution system.

Applications: Used in chokes for fluorescent lighting.; Employed in filter circuits and inductive sensors.

Additional Info: In a purely inductive circuit, the current lags by exactly $90^\circ$.. Option B is incorrect because the voltage is the reference quantity that leads the current in inductive loads.

Answer: A is correct — The current lags the applied voltage in an RL series circuit due to the inductive reactance.

Exam Tip: Remember 'ELI the ICE man': In an Inductor (L), E (Voltage) leads I (Current); in a Capacitor (C), I leads E.

Examoogle · Answer

Option B: Voltage

Correct Answer

Discussion (0)

Correct Answer

Related Questions

Discussion (0)