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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. 1.28 × 10^5 N/C
2. 1.28 × 10^6 N/C
3. 1.28 × 10^7 N/C
4. 1.28 × 10^4 N/C

Correct answer: 1.28 × 10^5 N/C

Solution

The electric field outside a spherical conductor is given by E = kQ/r², where k = 9 × 10^9 N·m²/C², Q = 3.2 × 10^-7 C, and r = 0.15 m. Substituting these values, E = (9 × 10^9 × 3.2 × 10^-7) / (0.15)² = 1.28 × 10^5 N/C.

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