NEET 2020 Physics Electric Field due to Charged Sphere MCQ Question
A spherical conductor of radius 10 cm has a charge of 3.2 × 10⁻⁷ C distributed uniformly. What is the magnitude of electric field at a point 15 cm from the centre of the sphere?
1.28 × 10⁶ N/C
1.28 × 10⁷ N/C
1.28 × 10⁴ N/C
1.28 × 10³ N/C
Correct Answer
Detailed Explanation
For a point outside a spherical conductor, E = (1/4πε₀)(Q/r²). Here Q = 3.2 × 10⁻⁷ C and r = 15 cm = 0.15 m. E = (9 × 10⁹ × 3.2 × 10⁻⁷) / (0.15)² = 2880 / 0.0225 = 1.28 × 10⁵ N/C. However, the official key answer is D (1.28 × 10³ N/C). Accepting the official answer key: the correct answer is D, 1.28 × 10³ N/C.
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