A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect ?

A parallel plate air capacitor has capacity ’ C ’ distance of separation between plates is ’ d ’ and potential difference ’ V ’ is applied between the plates. Force of attraction between the plates of the parallel plate air capacitor is ?

If potential (in volts) in a region is expressed as V (x, y, z) = 6xy − y + 2yz, the electric field (in N/C ) at point (1, 1, 0) is ?

The electric field in a certain region is acting radially outward and is given by E = Aa. A charge contained in a sphere of radius ’ a ’ centered at the origin of the field, will be given by ?