Consider following statements: Assertion: DC series motors are suitable for electric locomotives. Reason: DC series motors provide high starting torque. Of these statements:
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Answer & Explanation
Correct AnswerA. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Quick Explanation
A DC series motor develops very high starting torque because, before saturation, flux is approximately proportional to armature current and torque T∝ΦIa≈Ia². This makes it suitable for traction applications such as electric locomotives. Both assertion and reason are true, and the reason correctly explains the assertion: option A.
Formula / Key Relation
T∝ΦIa; unsaturated series motor Φ∝Ia → T∝Ia²
Detailed Explanation
Correct Answer
A — Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Concept and Reasoning
A DC series motor develops very high starting torque because, before saturation, flux is approximately proportional to armature current and torque T∝ΦIa≈Ia². This makes it suitable for traction applications such as electric locomotives. Both assertion and reason are true, and the reason correctly explains the assertion: option A.
Calculation / Key Relation
T∝ΦIa
unsaturated series motor Φ∝Ia → T∝Ia²
Exam Takeaway
Series motor + traction → remember high starting torque.
Common Mistake
Do not operate a DC series motor at no load because its speed can rise dangerously.
Quick Trick
Series motor + traction → remember high starting torque.
Common Mistake
Do not operate a DC series motor at no load because its speed can rise dangerously.
Exam Tip
Series motor + traction → remember high starting torque.
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