JAMB Physics 2019 Objective — Question 7
Question 7 of 40 from the Joint Admissions and Matriculation Board (JAMB) Physics 2019 Objective paper, with the correct answer and a full explanation.
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A little sag is left in overhead telephone wires because
- A. the sag allows for the effect of a rise in temperature due to heating effect of current flowing through them
- B. the sag allows for the effect of a fall in temperature of the surrounding atmosphereCorrect
- C. tact wires do not conduct sound easily
- D. the acceleration is constant throughout
Explanation
A fall in temperature causes contraction of the wire (while a rise causes expansion); the sag allows room for this contraction so the wire does not snap.
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