Two parallel plate air capacitors have the same separation. The plates of the first are squares of side 10cm.The plates of the second are squares of side 20cm.The ratio of the capacities respectively is

The capacity of a parallel plate condenser consisting of two plates each 10 cm square and are separated by a distance of 2mm is (Take air as the medium between the plate):

Two positive charges q₁=4x10^-6C and q₂=9x10^-6C are placed 10cm apart in air.The position of a third charge to be placed between them,such that there will be no resultant force on it is

A highly conducting sheet of aluminium foil negligible thickness is placed between the plates of a parallel plate capacitor.If thecapacitance before the insertion of foil was 10μF,its value after the insertion of foil will be

Two identical metal spheres possess +60C and -20C of charges.They are brought in contacts and then separated by 10cm.The force between them is

A sphere of radius 1m encloses a charge of 5μC. Another charge of -5μC is placed inside the sphere. The net electric flux would be

A condenser of capacity 10μF is charged to a potential of 500V. Its terminals are then connected to those of an uncharged condenser of capacity 40μF. The loss of energy in connecting them together is

A condenser 1μF is charged to a potential of 1000 volt. The energy stored in the condenser is:

A capacitor of capacity C is charged to a potential V.It is charged and isolated.Then distance between the plates is halved and then half the distance between them is filled with a metal slab.Then the capacitor

Two charges of 10μC and -90μC are separated by a distance of 24cm.Electrostatic field strength from the smaller charge is zero at a distance of