A hollow metallic sphere is charged by touching inside by charging rod.If the inside of the sphere is connected to a neutral gold leaf electroscope what will happen?
Answers
Explanation:
Charging by conduction involves the contact of a charged object to a neutral object. Suppose that a positively charged aluminum plate is touched to a neutral metal sphere. The neutral metal sphere becomes charged as the result of being contacted by the charged aluminum plate. Or suppose that a negatively charged metal sphere is touched to the top plate of a neutral needle electroscope. The neutral electroscope becomes charged as the result of being contacted by the metal sphere. And finally, suppose that an uncharged physics student stands on an insulating platform and touches a negatively charged Van de Graaff generator. The neutral physics student becomes charged as the result of contact with the Van de Graaff generator. Each of these examples involves contact between a charged object and a neutral object. In contrast to induction, where the charged object is brought near but never contacted to the object being charged, conduction charging involves making the physical connection of the charged object to the neutral object. Because charging by conduction involves contact, it is often called charging by contact.
Charging by Conduction Using a Negatively Charged Object
To explain the process of charging by contact, we will first consider the case of using a negatively charged metal sphere to charge a neutral needle electroscope. Understanding the process demands that you understand that like charges repel and have an intense desire to reduce their repulsions by spreading about as far as possible. A negatively charged metal sphere has an excess of electrons; those electrons find each other repulsive and distance themselves from each other as far as possible. The perimeter the sphere is the extreme to which they can go. If there was ever a conducting pathway to a more spacious piece of real estate, one could be sure that the electrons would be on that pathway to the greener grass beyond. In human terms, electrons living in the same home despise each other and are always seeking a home of their own or at least a home with more rooms.
Given this understanding of electron-electron repulsions, it is not difficult to predict what excess electrons on the metal sphere would be inclined to do if the sphere were touched to the neutral electroscope. Once the contact of the sphere to the electroscope is made, a countless number of excess electrons from the sphere move onto the electroscope and spread about the sphere-electroscope system. In general, the object that offers the most space in which to "hang out" will be the object that houses the greatest number of excess electrons. When the process of charging by conduction is complete, the electroscope acquires an excess negative charge due to the movement of electrons onto it from the metal sphere. The metal sphere is still charged negatively, only it has less excess negative charge than it had prior to the conduction charging process.