Question

Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R).

Assertion (A): The current drawn by the motor lags behind the voltage applied.
Reason (R): Motor is an inductive load.

In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is not the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Think about what property of a motor winding causes a phase difference between voltage and current.

Answer 1

The Correct Option is A

Step 1: Think in terms of a phasor diagram for an inductive circuit. Draw the supply voltage V along the reference axis. For a pure inductor, current always sits 90 degrees behind voltage; for a real motor winding that has both resistance and inductance, the current phasor sits somewhere between 0 and 90 degrees behind voltage, depending on how much resistance versus inductance the winding has.
Step 2: This angle between the voltage phasor and the current phasor is called the power factor angle. Whenever this angle is positive and the current phasor trails the voltage phasor, we say the current lags the voltage. That is exactly the situation for a motor, because its winding always carries some inductance from the coils that create the magnetic field.
Step 3: So the phasor picture directly confirms Assertion (A), the motor current lags the applied voltage.
Step 4: Now ask why this lag happens. It happens only because the winding is not purely resistive, it carries inductance. Remove the inductance and the current would line up with the voltage. So the inductive nature of the motor (Reason R) is the direct cause of the lag (Assertion A), not just a coincidentally true fact next to it.
Step 5: Both statements check out as true, and R is the mechanism that produces A.
\[\boxed{\text{Both (A) and (R) are true, and (R) correctly explains (A).}}\]