In a parallel plate capacitor, the capacity increases if :
In a parallel plate condenser if the distance between the plates is made half and the dielectric constant is doubled, then the capacity increases by a factor:
The plates of a parallel plate capacitor are charged to 200 V and then, the charging battery is disconnected. Now, a dielectric slab of dielectric constant 5 and thickness 4 mm is inserted between the capacitor plates. To maintain the original capacity, the increase in the separation between the plates of the capacitor is: