Two point charges of $+3 \mu \mathrm{C}$ and $-3 \mu \mathrm{C}$ are placed at a certain distance apart from each other. Electric potential at a distance 60 cm from the mid-point of dipole on axial line is 150 V , then the value of dipole length is

Electric field in the region is given by $$\mathbf{E}=\left(M / x^4\right) \hat{\mathbf{i}}$$, then the correct expression for the potential in the region is (assume potential at infinity is zero)

The net electric force on a charge of $$+3 \mu \mathrm{C}$$ at the mid-point on the line joining two charges of magnitude $$+2 \mu \mathrm{C}$$ and $$-2 \mu \mathrm{C}$$ separated by the distance of $$6 \mathrm{~mm}$$, is

A hollow sphere of radius $$0.1 \mathrm{~m}$$ has a charge of $$5 \times 10^{-8} \mathrm{C}$$. The potential at a distance of 5 $$\mathrm{cm}$$ from the centre of the sphere is $$\left(\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9 \mathrm{Nm}^2 \mathrm{C}^{-2}\right)$$