Correct Answer

Concept & PrincipleElectricalBasic Electrical

Option A

Current

Quick Summary: In a pure inductive circuit, the current lags the applied voltage by exactly 90 degrees or $\frac{\pi}{2}$ radians. This occurs because the inductor opposes any change in current, resulting in a phase shift where the voltage peak leads the current peak.

💡 Explanation

In a pure inductive circuit, the current lags the applied voltage by exactly 90 degrees or $\frac{\pi}{2}$ radians. This occurs because the inductor opposes any change in current, resulting in a phase shift where the voltage peak leads the current peak.

🔢 Key Formulas

$X_L = 2\pi f L$ — Inductive Reactance in ohms

$v(t) = L \frac{di}{dt}$ — Voltage-Current relationship for an inductor

⚙️ Working Principle

According to Faraday's Law of Electromagnetic Induction, the voltage across an inductor is given by $v(t) = L \frac{di}{dt}$ . When a sinusoidal voltage $v = V_m \sin(\omega t)$ is applied, the current $i(t)$ becomes $\frac{V_m}{\omega L} \sin(\omega t - 90°)$ . The back-EMF generated by the change in current causes the current to be delayed relative to the voltage.

📌 Key Points

▸
The phase angle difference is exactly 90 degrees.
▸
The power factor of a pure inductor is zero (lagging).
▸
Inductors store energy in the form of a magnetic field.
▸
Average power consumed by a pure inductor over one cycle is zero.

✅ Advantages

▸
Provides high impedance to high-frequency signals
▸
Essential for filter and oscillator circuit design

❌ Disadvantages / Limitations

▸
Cannot dissipate real power
▸
Physical inductors always possess internal resistance causing losses

🛠️ Applications / Uses

▸
AC motor starting circuits
▸
RF tuning and frequency filtering
▸
Transformer windings

📄 Additional Information

▸
Option B is incorrect because voltage leads the current in an inductive circuit, whereas current leads voltage only in a capacitive circuit.
▸
The term 'lagging' refers to the time-domain peak of the current occurring after the peak of the voltage.

📊 Diagram / Illustration

✅

A is correct — In a pure inductive circuit, the current waveform lags behind the applied voltage waveform by a phase angle of $90°$ .

Core Concepts Used

Click any tag to open in AI Tutor

Inductive Reactance Phase Lag Faraday's Law

💡 EXAM TIP

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

Discussion (0)

Loading discussion...

Prev Next

Correct Answer

Related Questions

Discussion (0)