Take a thin aluminium curtain rod with ball ends fitted for hanging the curtain. Cut out a piece of length about $20 \mathrm{~cm}$ with the ball at one end and flattened the cut end.

Take a large bottle that can hold this rod and a cork which will fit in the opening of the bottle. Fit the cork in the bottle with about $5 \mathrm{~cm}$ of the ball end projecting about the cork. Fold a small, thin aluminium foil (about $6 \mathrm{~cm}$ in length) in the middle and attach it to the flattened end of the rod by cellulose tape.

Put a paper scale inside the bottle in advance to measure the separation of leaves. The separation is a rough measure of the amount of charge on the electroscope.