Question

A ball of charge q is placed in a hollow conducting uncharged sphere. After this, the sphere is connected with earth for a short time and the ball has not been brought into contact with the sphere. What charge will the sphere have after these operations? Where and how will this charge be distributed?

Answer 1

Hint: Electric charge is the result of excess or insufficiency of electrons as compared to protons, when a charged body is brought close to an uncharged body but they don't touch each other, then the surface of the uncharged body gets a charge of opposite sign and the bodies start attracting each other. This is known as charge induction.


Complete step by step solution:











i. When we bring a charge q at the centre of a sphere, charges −q and +q will be induced on the inner surface and an outer surface, respectively, as shown in the figure.

ii. After earthing, +q will be transferred to earth as shown in the figure.

iii. After removing the earthing and charge q from the centre, -q will be distributed uniformly on the external surface of the sphere as shown in the figure. So finally, the sphere will have charge -q.


Note:There are three ways to charge an object:
a. Friction: When insulating materials rub against each other, they may become electrically charged.
b. Conduction: Charging by conduction involves the contact of a charged object to a neutral object.
c. Induction: Induction charging is a method used to charge an object without actually touching the object to any other charged object.