Two conducting spheres of radii $r_1$ and $r_2$ have equal surface charge densities. The ratio of their charges is ___.

Linear charge density of a half ring varies with $\text{θ}$ as $\lambda ={\lambda }_0\cos \text{θ}.$ Then find the total charge on the ring.

If linear charge density of a wire of length $L$ depends on distance $x$ from one end as $\text{λ}=\frac{{\text{λ}}_{0}x}{L},$ then find the total charge on the wire.

The Gaussian surface used for calculating the electric field due to a charge distribution is