Correct Answer

Concept & PrincipleElectricalBasic Electrical

Option B

Voltage

Quick Summary: In a purely capacitive circuit, the current leads the voltage by a phase angle of $90^\circ$ (or $\frac{\pi}{2}$ radians). Conversely, this means the voltage lags behind the current by the same phase angle.

💡 Explanation

In a purely capacitive circuit, the current leads the voltage by a phase angle of $90°$ (or $\frac{\pi}{2}$ radians). Conversely, this means the voltage lags behind the current by the same phase angle.

🔢 Key Formulas

$i(t) = C \frac{dv(t)}{dt}$ — Fundamental capacitor current equation

$X_C = \frac{1}{2\pi f C}$ — Capacitive Reactance

⚙️ Working Principle

In a capacitor, the current is proportional to the rate of change of voltage, expressed as $i = C \frac{dv}{dt}$ . When a sinusoidal voltage $v = V_m \sin(\omega t)$ is applied, the resulting current becomes $i = \omega C V_m \sin(\omega t + 90°)$ . Thus, the current wave reaches its peak before the voltage wave, causing the voltage to lag.

📌 Key Points

▸
In a pure capacitor, phase difference $\phi = 90°$ .
▸
Power factor in a pure capacitor is zero leading.
▸
Capacitors oppose changes in voltage ( $V = \frac{1}{C} \int i dt$ ).
▸
The voltage wave reaches zero at a later time than the current wave.

✅ Advantages

▸
Used for power factor correction in inductive circuits.
▸
Energy storage in electric fields.

❌ Disadvantages / Limitations

▸
Causes leading power factor in transmission lines.
▸
Non-linear characteristics in transient states.

🛠️ Applications / Uses

▸
Filtering in power supplies.
▸
Capacitor start motors.
▸
Coupling and decoupling circuits.

📄 Additional Information

▸
In an inductive circuit, the voltage leads the current.
▸
For a purely resistive circuit, voltage and current are in phase.
▸
Option A is incorrect because current leads, it does not lag.

📊 Diagram / Illustration

✅

B is correct — In a purely capacitive circuit, the voltage lags behind the current by a phase angle of $90°$ .

Core Concepts Used

Click any tag to open in AI Tutor

Capacitive Reactance Phase Angle AC Circuit Analysis

💡 EXAM TIP

Use the mnemonic 'ICE' to remember phase relationships: In an Inductor (I), Current (C) lags Voltage (E); in a Capacitor (C), Current (I) leads Voltage (E).

Discussion (0)

Loading discussion...

Prev Next

Correct Answer

Related Questions

Discussion (0)