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An electric motor operating on a 60 volt D.C supply draws a current of 10 amp. If the efficiency of the motor is 50%, the resistance of its windings is
Options
(a) 3 ohm
(b) 6 ohm
(c) 15 ohm
(d) 30 ohm
Correct Answer:
3 ohm
Explanation:
Efficiency n = 50 %
e = E/2 ⇒ I = (E – e) / R = [E – (E/2)] / RA = E / 2R
10 = 60 / 2R ⇒ R = 60 / (2 × 10) = 3 ohm
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Topics: Current Electricity
(136)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- A thin circular ring of mass M and radius R rotates about an axis through its centre
- A transformer of 100% efficiency has 200 turns in the primary coil and 40000 turns
- If the earth shrink such that its mass does not change but radius decreases to one
- Perfectly black body radiates the energy 18 J/s at 300K. Another ordinary body of e=0.8
- The friction of the air causes a vertical retardation equal to 10%
Topics: Current Electricity (136)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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