DC Motor

DC Motor is a Science & Technology concept from the MPSC syllabus, tested in 2 past MPSC questions (2023). Below are those real questions with their correct answers and explanations, plus the concepts worth being comfortable with first.

Real questions

Years tested

1 · 2023–2023

In context

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Asked in

2023

What you need to know first

Electromagnetic inductionMotorsMotor working principle

Real questions that test this

मोटरमध्ये माघारी विद्युतगामकाचे महत्व काय आहे ? Why is back emf important in a motor ?

1)यामुळे मोटरचा वेग वाढतो / It increases the speed of the motor

2)यामुळे मोटरमधील विद्युतप्रवाह कमी होतो / It reduces the current in the motor✓ Correct

3)हे उपयुक्त यांत्रिक कार्य निर्माण करते / It generates useful mechanical work

4)यामुळे मोटरचा पीडन परीबल कमी होतो / It reduces the torque of the motor

Back emf in a DC motor opposes the supplied voltage, regulates the current drawn, and helps control the speed of the motor automatically.

जेव्हा मोटारीतील यांत्रिक भार वाढतो, तेव्हा माघारी विद्युतगामकाचे काय होते ? What happens to the back emf, when the mechanical load on the motor increases ?

1)ते तसेच राहते / It remains the same

2)ते वाढते / It increases

3)ते कमी होते / It decreases✓ Correct

4)त्याचा मोटरवर काहीही परिणाम होत नाही / It has no effect on the motor

When mechanical load on a DC motor increases, the speed decreases, which in turn decreases the back emf (Eb) as Eb is directly proportional to speed.

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