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# Some equip-potential surfaces are shown in figures. What can you say about the magnitude and direction of the electric field

The electric field will be at angle making an angle $120^{\circ}$ with x-axis.
Magnitude of electric field $E \cos 120^{\circ}=-\large\frac{(20-10)}{(20-10) \times 10^{-2}}-$$E . \large\frac{1}{2} =-\large\frac{-10}{0.10} => E= 200 V/m Direction of electric field will be radially outward, similar to a point charge kept at the centre, i.e V= \large\frac{kq}{r} When V=60 V=\large\frac{kq}{(0.1)} Hence potential at any distance from the center. V(r) =\large\frac{6}{r} Hence E= -\large\frac{dV}{dr} = \bigg( \large\frac{6}{r^2} \bigg)$$V/m$