Question

Consider the following statements related to electric circuits:
A. Leading and lagging current are phenomena that occur as a result of direct current.
B. In the case of a circuit having only resistances, the voltages and currents are in phase
C. In a purely capacitive circuit, the current will lead the voltage
D. In a purely inductive circuit, the current will lag the voltage
Choose the correct answer from the options given below:

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

Hint:

Use the classic mnemonic CIVIL to remember phase relationships:
- In a Capacitor, I (current) leads V (voltage) \(\rightarrow\) CIV.
- V (voltage) leads I (current) in an Linductor \(\rightarrow\) VIL.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
In AC circuits, the phase relationship between voltage and current depends on the type of load elements present in the circuit.
These phase shifts do not occur in steady-state DC circuits because DC voltage and current do not change periodically over time.

Step 2: Detailed Explanation:
Let us analyze each statement:
- Statement A: "Leading and lagging current are phenomena that occur as a result of direct current."
This is incorrect.
Leading and lagging currents are phase shift phenomena that only occur in Alternating Current (AC) circuits due to the reactive properties of inductors and capacitors.
- Statement B: "In the case of a circuit having only resistances, the voltages and currents are in phase."
This is correct.
Resistors do not store electrical energy or cause phase shifts. The current through a resistor directly tracks the voltage across it, meaning the phase angle difference is zero (\(\theta = 0\)).
- Statement C: "In a purely capacitive circuit, the current will lead the voltage."
This is correct.
In a purely capacitive circuit, the current leads the voltage by exactly \(90^\circ\) because the capacitor must charge first before a voltage difference can build across its plates.
- Statement D: "In a purely inductive circuit, the current will lag the voltage."
This is correct.
In a purely inductive circuit, the current lags the voltage by exactly \(90^\circ\) because the inductor opposes changes in current, delaying the current relative to the voltage.
Therefore, statements B, C, and D are correct.

Step 3: Final Answer:
The correct option is (C).