The electric field intensity $E$ at a distance of 3 m from a uniform long straight wire of linear charge density $0.2 \mu \mathrm{~cm}^{-1}$ is

When a parallel plate capacitor is charged up to 95 V , its capacitance is $C$. If a dielectrtic slab of thickness 2 mm is inserted between plates and distance between the plates is increased by 1.6 mm such that the same potential difference is maintained. The dielectric constant of the material (slab) is

The capacitance of an isolated sphere of radius $r_1$ is increased by 5 times, when it is enclosed by an earthed concentric sphere of radius $r_2$. The ratio of their radii is

The charge $q$ (in coulomb) passing through a $10 \Omega$ resistor as a function of time $t$ (in second) is given by $q=3 t^2-2 t+6$. The potential difference across the ends of the resistor at time $t=5 \mathrm{~s}$ is