Specification:
Foil electroscope (1 pair)
Size: base length 115* width 73* total height 148mm
Material: plastic, metal
Weight: A set of about 295g

Check if an object is positively or negatively charged:
Let the electroscope's metal foil be charged with a known charge (positive or negative) and thus open at an angle, and then move the object to be examined closer to the top of the electroscope (without touching it). If the angle at which the foil is opened increases, the object will be charged with the same charge as the electroscope. If the opening angle of the metal foil is thus reduced, the charge on the object is different from that on the electroscope.

Demonstrate conductors and insulators:
Take two identical electroscopes and make one of them electrified, so that the metal foil is opened at a certain angle (the more electricity is charged, the greater the angle of opening of the metal foil, the better the demonstration effect). The other is uncharged, because the electric charge carried by the appliance is transmitted to the other electroscope through the metal rod, so the metal is a conductor. If a glass rod or a hard rubber rod is used to connect the tops of the two electroscopes, the opening angle of the charged electroscope metal foil will not change, and the uncharged electroscope metal foil will not open either. This shows that charge cannot be transferred through glass rods or hard rubber rods, so both glass and hard rubber are insulators.