A simple apparatus to detect charge on a body is the gold-leaf electroscope. It consists of a vertical metal rod housed in a box, with two thin gold leaves attached to its bottom end.
When a charged object touches the metal knob at the top of the rod, charge flows on to the leaves and they diverge. The degree of divergence is an indicator of the amount of charge.
The gold leaves are extremely thin conducting foils which have low mass per unit area and are flexible, therefore, they respond very quickly to small electrostatics forces.
This instrument can also be used check the polarity of charge and to measure the potential difference.
Some of these questions which may be asked in your Board Examination 2012-2013
Q1: Can we use aluminium leaves instead of gold leaves in Gold Leaf Electroscope?
Q2: Why gold leaves are preferred for Gold Leaf Electroscope?
Q3: What is the basic purpose of Gold Leaf Electroscope?
Q4: How can we check the polarity of charge by Gold Leaf Electroscope?
Answer these questions in comment box and help your friends