Match List-I with List-II
| List-I | List-II |
| AC circuit | Features |
| (A) Only resistor in a circuit | (I) Current leads or lags the voltage |
| (B) Only capacitor in a circuit | (II) Voltage and current are in phase |
| (C) Only inductor in a circuit | (III) The current lags the voltage by \( \frac{\pi}{2} \) |
| (D) Series LCR circuit \( X_C \ne X_L \) and \( R \ne 0 \) | (IV) The current leads the voltage by \( \frac{\pi}{2} \) |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A) - (II), (B) - (IV), (C) - (III), (D) - (I)
The phase between voltage and current in an ac circuit depends on the element: a resistor gives no phase difference, while a capacitor and an inductor give \( \pi/2 \) in opposite senses.
(A) Only resistor in a circuit — this matches (II) Voltage and current are in phase. The current in a resistor follows the voltage at every instant.
(B) Only capacitor in a circuit — this matches (IV) The current leads the voltage by \( \frac{\pi}{2} \). The current is \( dq/dt \), largest when the voltage is zero, so it reaches its peak a quarter cycle earlier.
(C) Only inductor in a circuit — this matches (III) The current lags the voltage by \( \frac{\pi}{2} \). The induced emf opposes the rise of current, so the current reaches its peak a quarter cycle later.
(D) Series LCR circuit \( X_C \ne X_L \) and \( R \ne 0 \) — this matches (I) Current leads or lags the voltage. The phase angle is given by the formula below: the current lags if \( X_L \gt X_C \) and leads if \( X_C \gt X_L \), by an angle less than \( \pi/2 \).
\( \displaystyle \tan\phi = \frac{X_L - X_C}{R} \)
NCERT (2026-27):
AC Voltage Applied to a Resistor – “… Clearly, the voltage and current are in phase with each other.”
AC Voltage Applied to a Capacitor – “… Thus, we see that in the case of an inductor, the current lags the voltage by \( \pi/2 \) and in the case of a capacitor, the current leads the voltage by \( \pi/2 \).”
Phasor-Diagram Solution – “… If \( X_C \gt X_L \), \( \phi \) is positive and the circuit is predominantly capacitive. Consequently, the current in the circuit leads the source voltage. If \( X_C \lt X_L \), \( \phi \) is negative and the circuit is predominantly inductive. Consequently, the current in the circuit lags the source voltage.”