Q. The electric potential V at any point (x, y, z), in meters in space is given by V = 4x² volt. The electric field at the point (1, 0, 2) in volt/meter, is
A) 16 along positive X-axis
B) 8 along negative X-axis
C) 8 along positive X-axis
D) 16 along negative X-axis
Explanation
[Solution from source] E = −dV/dx = −8x, which at x = 1 m is −8 V/m, i.e. 8 V/m along the negative x-axis. The value 16 V/m comes from wrong differentiation, and the positive direction ignores the minus sign in E = −∇V. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.