Question

In an ac circuit, the instantaneous current is zero,when the instantaneous voltage is maximum. In this case, the source may be connected to :
A. pure inductor.
B. pure capacitor.
C. pure resistor.
D. combination of an inductor and capacitor.
Choose the correct answer from the options given below :

• A. A, B and C only
• B. B, C and D only
• C. A and B only
• D. A, B and D only

Answer 1

Answer: (D)

A, B and D only

Answer 2

Understanding the Phase Relationship in AC Circuits:
In an AC circuit: For a pure inductor, the current $I$ lags the voltage $V$ by $90^\circ$ (or \(\frac{\pi}{2} ) radians).
For a pure capacitor, the current $I$ leads the voltage $V$ by $90^\circ$. For a pure resistor, the current and voltage are in phase, meaning that they reach zero and maximum values simultaneously.

Condition for Instantaneous Current to be Zero When Voltage is Maximum:
The given condition (current is zero when voltage is maximum) implies a $90^\circ$ phase difference between the current and voltage.
This situation occurs in:
- A pure inductor, where current lags the voltage by $90^\circ$.
- A pure capacitor, where current leads the voltage by $90^\circ$.
- A combination of an inductor and capacitor (LC circuit), where the phase difference can also result in current being zero when voltage is maximum.

Conclusion:
Since this phase relationship is possible in a pure inductor, pure capacitor, or an LC combination, the correct answer is Option (4): A, B, and D only.