The scalar product of electric field intensity and area vector through which the line of force emerges is ___________.

In the figure given below, two conducting concentric spherical shells are shown. If the electric potential at the centre is $20 \mathrm{V}$ and the electric potential of the outer shell is $5 \mathrm{V}$ then the potential of the inner shell is

A metallic solid sphere is placed in a uniform electric field. The path followed by the lines of force is,

A charge $Q$ is enclosed by a Gaussian spherical surface of radius $R$. If the radius is doubled, then the outward electric flux will 

Find the flux through the Gaussian surface, given that the radius of the circle is $R$.