Question

The electric potential V at any point x, y, z (all in metres) in space is given by V = 4x²volt. The electric field at the point (1m, 0, 2m) in volt/metre is

• A. 8 along negative X-axis
• B. 8 along positive X-axis
• C. 16 along negative X-axis
• D. 16 along positive Z-axis

Answer 1

Answer: (A)

8 along negative X-axis

Answer 2

By using $E = - \frac{dV}{dx}$ ⇒ $E = - \frac{d}{dx}(4x^{2}) = - 8x$. Hence at point (1m, 0, 2m). E = – 8 volt/m i.e. 8 along – ve x-axis.