WAEC Physics 2014 Objective — Question 42
Question 42 of 50 from the West African Examinations Council (WAEC) Physics 2014 Objective paper, with the correct answer and a full explanation.
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Two identical charges situated 20cm apart in vacuum repel each other with a force of 1.0N. Calculate the value of each charge. [(4πε₀)⁻¹=9×10⁹ N m²C⁻²]
- A. 2.1 µCCorrect
- B. 3.6 µC
- C. 4.0 µC
- D. 4.4 µC
Explanation
F=kq²/r² ⟹ q²=Fr²/k = (1.0×0.2²)/(9×10⁹) = 4.44×10⁻¹²; q ≈ 2.1×10⁻⁶C = 2.1µC.
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