91Ó°ÊÓ

The physical characteristic of matter that allows it to feel a force when exposed to an electromagnetic field is called electric charge.

The electric charge is denoted by $\mathrm{Q}$.It has two types: Positive charge and Negative Charge.

To put a net negative charge on an insulated metal sphere from a negatively charged object, touch the sphere with negatively charged object. This will result in both objects being negatively charged.

Hence, the metal sphere gets a net negative charge.

To put a net positive charge on an insulated metal sphere from a negatively charged object, use induction. Place the negatively charged object to the vicinity of one side of the sphere. This make charges on the sphere polarize, the electrons group on the other side. With a grounded wire, conduct the electrons away from the sphere. Then remove the wire.

Hence, the metal sphere gets a net positive charge.