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The gold-leaf electroscope is the simple apparatus to detect charge on the body. 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.Two  white paper strips is used for  the working of the apparatus and 

fold the strips into half   hold the strip by pinching it at the fold.The two halves move apart.This shows that the strip has acquired charge on ironing. when  folding  it into half, both the halves have the same charge. Hence they repel each other. 

 On charging the curtain rod by touching the ball end with an electrified body, charge is transferred to the curtain rod and the attached aluminium foil. Both the halves of the foil get similar charge and therefore repel each other. The divergence in the leaves depends on the amount of charge on them.