Q. A spherical conductor of radius 10 cm has a charge of $3.2 \times 10^{-7}$ C distributed uniformly. What is the magnitude of electric field at a point 15 cm from the centre of the sphere ? ($\frac{1}{4\pi\epsilon_0} = 9 \times 10^9$ N $m^2/C^2$)
A) $1.28 \times 10^5$ N/C
B) $1.28 \times 10^6$ N/C
C) $1.28 \times 10^7$ N/C
D) $1.28 \times 10^4$ N/C
Explanation
[Solution] $E = \frac{kQ}{r^2} = \frac{9 \times 10^9 \times 3.2 \times 10^{-7}}{0.0225} = 1.28 \times 10^5$ N/C. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.