In a particular experiment, a high voltage is created by charging an isolated metal sphere as shown in the fig.
The sphere has diameter 42 cm and any charge on its surface may be considered as if it were concentrated at its center. The air surrounding the sphere loses its insulating properties, causing a spark, when the electric field exceeds `20 kV cm^-1` . Calculate for the charged sphere when a spark is about to occur the charge on the sphere and its potential.

In a particular experiment, a high vltage is created by charging an isolated metal sphereas shown in the fig. The sphere has diameter 42 cm and any charge on its surface may be considered as if IT were concentrated at its centre. The air surrounding the sphere loses its insultaing properties, causing a spark, when the electric field exceeds 20 kV cm^-1 by reference to an atom in the air, suggest the mechanism by which the electric field causes the air to become conducting.

A solid metal sphere of radius r has charge +Q. The sphere has radius 36 cm This charge is one the surface of the sphere but it may be considered to be a point charge at its centre. A spark suddenly connects the metal sphere in to the earth, causing the potnetial of the sphere to be reduced from 7.0 xx 10^5V to 2.5 xx 10^5V . Calculate the energy dissipated in the spark.

Find the surface area of a sphere of diameter: 28cm

Can a metal sphere of radius 1 cm hold a charge of 1 C?

Find the surface area of a sphere of diameter 14 cm?

A solid metal sphere of radius r has charge +Q. This charge is one the surface of the sphere but it may be considered to be a point charge at its centre. Suggest, why your calculation in (a) for the metal sphere would not apply to a plastic sphere.

A small charged metal sphere is situated in an earthed metal box. Illustrates the electric field between the sphere and the metal box. The radius r of the sphere is 2.4 cm. The magnitude of the charge q on the sphere is 0.76 n C.

A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is 1.5xx 10^3N//C and points radially inward, what is the net charge on the sphere?