Answer to Question #33430 in Electromagnetism for meenakshi moun
when earth has its own magnetic field then why it is not considered a charged object?
Earthhas a charge(-), but ionosphere, also, has charge(+), that's why system "earth-ionosphere" is quasi-neutral.
Here's some details. Earth Charge. Since 1917 scientists have known that the earth's surface is charged with negative electricity, but no one knew for sure what keeps it charged. In areas of fair weather, an electric current flows between the earth and the air in a direction which would tend to dissipate the charge. It is not much of a current: only about 1,500 amperes, not much more for the entire earth than flows in a few power lines. But the electricity taken from the earth must be restored somehow or the earth's electric charge would soon drain away. An obvious guess is that thunderstorms somehow restore the lost charge, but no one had proved it. Three years ago the institution borrowed airplanes from the Air Force and began to measure electrical stirring in the still air above active thunderheads. Sure enough, the instruments showed a current moving in the opposite direction to the current in fair-weather areas. The scientists figured that all the thunderstorms going on at one time generate a net current of about 1,500 amperes, just enough to balance the drain and keep the earth's charge constant.