A metal can sits on an electroscope. If a charged sphere is now brought up to the open end of the can and carefully held inside, the induced charge on the outside surface of the can is shown on the electroscope. If the sphere is moved, the charge disappears. If the sphere comes in contact with the inside of the can, no jump will be seen on the electroscope, but the charge will remain on the can when the sphere is removed. Be careful not to let the sphere come too close to the can a spark will jump accidentally.