Q. The electric potential at a point in free space due to a charge Q coulomb is Q × 10¹¹ volts. The electric field at that point is
A) 12πε₀Q × 10²² volt/m
B) 4πε₀Q × 10²² volt/m
C) 12πε₀Q × 10²⁰ volt/m
D) 4πε₀Q × 10²⁰ volt/m
Explanation
[Solution from source] V = Q/(4πε₀r) = Q × 10¹¹ gives r = 1/(4πε₀ × 10¹¹). Then E = V/r = Q × 10¹¹ × 4πε₀ × 10¹¹ = 4πε₀Q × 10²² V/m. The 10²⁰ forms come from mishandling the power of ten. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.