Match List-I with List-II
| List-I | List-II |
| AC circuit | Phase angle |
| (A) Phase difference between current and voltage in a pure inductive ac circuit | (I) zero |
| (B) Phase difference between current and voltage in a pure resistive ac circuit | (II) \( \pi/2 \), current lags voltage |
| (C) Phase difference between current and voltage in a pure capacitive ac circuit | (III) \( \tan^{-1}\left(\frac{X_L - X_C}{R}\right) \) |
| (D) Phase difference between current and voltage in a series LCR circuit | (IV) \( \pi/2 \), current leads voltage |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A) - (II), (B) - (I), (C) - (IV), (D) - (III)
The phase between current and voltage depends on the element: a resistor gives none, while an inductor and a capacitor shift the current by a quarter cycle in opposite senses.
(A) Phase difference between current and voltage in a pure inductive ac circuit — this matches (II) \( \pi/2 \), current lags voltage. The self-induced emf opposes the rise of current, so the current reaches its peak a quarter cycle after the voltage.
(B) Phase difference between current and voltage in a pure resistive ac circuit — this matches (I) zero. The current \( V/R \) follows the voltage at every instant, so they are in phase.
(C) Phase difference between current and voltage in a pure capacitive ac circuit — this matches (IV) \( \pi/2 \), current leads voltage. The current \( dq/dt \) is largest when the voltage is zero, so it peaks a quarter cycle earlier.
(D) Phase difference between current and voltage in a series LCR circuit — this matches (III) \( \tan^{-1}\left(\frac{X_L - X_C}{R}\right) \). From the phasor diagram, the voltage across \( L \) and \( C \) together is \( I(X_L - X_C) \) and across \( R \) is \( IR \), so
\( \displaystyle \tan\phi = \frac{X_L - X_C}{R} \)
NCERT (2026-27):
Representation of AC Current and Voltage by Rotating Vectors — Phasors – “… From Fig. 7.4(a) we see that phasors V and I for the case of a resistor are in the same direction. This is so for all times. This means that the phase angle between the voltage and the current is zero.”
AC Voltage Applied to a Capacitor – “… Thus, we see that in the case of an inductor, the current lags the voltage by π/2 and in the case of a capacitor, the current leads the voltage by π/2.”