Gce Model Questions Vol1 2024 Physics Question 45

Practice objective / multiple choice question 45 from the 2024 Gce Model Questions Vol1 Physics examination.

Gce Model Questions Vol1 2024 Physics Objective / Multiple Choice Medium Difficulty
Question 45 GCE_MODEL_QUESTIONS_VOL1 • 2024 • PHYSICS • objective

A small DC motor is rated at a supply voltage of \(6.0\ \text{V}\). At its rated load it draws a current of \(2.0\ \text{A}\) and its efficiency at this load is \(80\%\). Determine (a) the internal resistance of the motor, and (b) the magnitude of the back‑emf generated by the motor when it is operating at its rated load.

Answer Options

A. Internal resistance r = 3.0 \Omega; back‑emf = 0 V
B. Internal resistance r = 0.30 \Omega; back‑emf = 5.4 V
Correct Answer C. Internal resistance r = 0.60 \Omega; back‑emf = 4.8 V
D. Internal resistance r = 0.75 \Omega; back‑emf = 4.5 V
Correct Answer
C
Correct Option:
Internal resistance r = 0.60 \Omega; back‑emf = 4.8 V

About This Question

This is Gce Model Questions Vol1 2024 Physics Question 45. It is one of the objective questions from the 2024 Gce Model Questions Vol1 Physics examination.

Difficulty level: Medium .

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