Q.
The metal knob of a gold leaf electroscope is touched with
a positively charged rod. When it is taken away the leaves
stay separated. Now the metal knob is touched by
negatively charged rod. The separation between the leaves
On touching the metal knob with a positively charged
rod some electrons from the gold leaves get transferred to
the rod making gold leaves positively charged and they
get separated. When a negatively charged rod is touched
with metal knob some negative charge flows to the gold
leaves lessening the positive charge there and the
separation between the leaves decreases.