A conducting sphere of radius $10cm$ is charged to $10\mu C$. Another unchanged sphere of radius $20cm$ is allowed to touch it for some time. After that if the spheres are separated, then surface density of charges, on the spheres will be in the ratio of

In the given figure, the capacitors $C_1, C_3, C_4, C_5$

have a capacitance, $4 \mu \mathrm{F}$ each. If the capacitor $C_2$ has a capacitance, $10 \mu \mathrm{F}$ , then effective capacitance between $A$ and $B$ will be:

A capacitor of $0.2 \mu \mathrm{F}$ capacitance is charged to $600 \mathrm{V}$. After removing the battery, it is connected with a $1.0 \mu \mathrm{F}$ capacitor in parallel, then the potential difference across each capacitor will become :

Mean electric energy density between the plates of a charged capacitor is :

Here q = Charge on capacitor

A = Area of each plate of the capacitor

If potential difference across a capacitor is changed from 15 V to 30 V, work done is W. The work done when potential difference is changed from 30 V to 60 V, will be :

A capacitor is connected to a 10 V battery. The charge on plates is 40 µC when medium between plates is air. The charge on the plates become 100 µC when the space between the plates is filled with oil. The dielectric constant of oil is :