Post-UTME Physics 2018 Objective — Question 3
Question 3 of 20 from the Post-UTME Screening (Post-UTME) Physics 2018 Objective paper, with the correct answer and a full explanation.
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What is the resistance of a wire 220cm long and 0.7mm in diameter at 20 degrees C? (The resistivity of the material at 20 degrees C is 3.5x10^-6 ohm.cm)
- A. 0.20 ohmCorrect
- B. 5.00 ohm
- C. 0.20 ohm (variant)
- D. 5.00 ohm (variant)
Explanation
Radius = 0.035cm. Area = pi*r^2 = pi*(0.035)^2 = 0.003848 cm^2. R = (resistivity x length)/area = (3.5x10^-6 x 220)/0.003848 = 0.20 ohm.
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