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Physics

Chapter 4 - Alternating Current AC Circuits

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Chapter 5 - Dual Nature of Wave and Particle

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Chapter 6 - Atomic Spectra and X-Rays

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Chapter 7 - Lasers and Principles

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Chapter 8 - Modern Electronics and Semiconductors

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Quiz

Lesson 4: The Electric Transformer and Electric Motor (DC Motor) — Picture questions (exam style)

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1.
A d.c. motor of coil resistance 1 Ω runs on 24 V drawing 4 A. Which option is correct? (no friction)
A d.c. motor of coil resistance 1 Ω runs on 24 V drawing 4 A. Which option is correct? (no friction)
back emf = 4 V, efficiency = 100%, starting current = 24 A
back emf = 20 V, efficiency = 16.7%, starting current = 24 A
back emf = 20 V, efficiency = 83.3%, starting current = 24 A
back emf = 28 V, efficiency = 83.3%, starting current = 24 A