Question

The grid (each square of 1m × 1m), represents a region in space containing a uniform electric field. If potentials at point O, A, B, C, D, E, F, G, H are respectively 0, –1, –2, 1, 2, 0, –1, 1 and 0 volts. find the electric field intensity.

• A. ($\widehat{i}$+ $\widehat{j}$)V/m
• B. ($\widehat{i}$ – $\widehat{j}$)V/m
• C. (–$\widehat{i}$+ $\widehat{j}$)V/m
• D. (–$\widehat{i}$ – $\widehat{j}$)V/m

Answer 1

Answer: (C)

(–$\widehat{i}$+ $\widehat{j}$)V/m

Answer 2

Charge on the sphere = $4\pi R^{2}\sigma$

Where σ = surface density = charge per unit Surface area

$E = \frac{1}{4\pi\varepsilon_{0}} \times \frac{ch\arg e}{R^{2}}$ = $\frac{1}{4\pi\varepsilon_{0}} \times \frac{4\pi R^{2}\sigma}{R^{2}} = \left( \frac{\sigma}{\varepsilon_{0}} \right)$