The equivalent capacitance of the combination shown in the figure is: 

1.	\(\dfrac{C}{2}\)	2.	\(\dfrac{3C}{2}\)
3.	\(3C\)	4.	\(2C\)

Two charged spherical conductors of radii \(R_1\) and \(R_2\) are connected by a wire. The ratio of surface charge densities of spheres \(\left ( \frac{\sigma _{1}}{\sigma _{2}}\right )\) is:

Twenty seven drops of same size are charged at \(220~\text{V}\) each. They combine to form a bigger drop. Calculate the potential of the bigger drop:
1. \(1520~\text{V}\)
2. \(1980~\text{V}\)
3. \(660~\text{V}\)
4. \(1320~\text{V}\)

A parallel plate capacitor with cross-sectional area \(A\) and separation \(d\) has air between the plates. An insulating slab of the same area but the thickness of \(\dfrac{d}{2}\) is inserted between the plates as shown in the figure having a dielectric constant, \(K=4\). The ratio of new capacitance to its original capacitance will be:

A hollow metal sphere of radius \(R\) is given \(+Q\) charges to its outer surface. The electric potential at a distance \(\dfrac{R}{3}\) from the centre of the sphere will be:
1. \(\dfrac{1}{4\pi \varepsilon_0}\dfrac{Q}{9R}\)
2. \(\dfrac{3}{4\pi \varepsilon_0}\dfrac{Q}{R}\)
3. \(\dfrac{1}{4\pi \varepsilon_0}\dfrac{Q}{3R}\)
4. \(\dfrac{1}{4\pi \varepsilon_0}\dfrac{Q}{R}\)