题目让装有绝缘柄的金属小球A带上正电，去接触验电器的金属球B，发现验电器金属箔的张角变小．由此可见验电器原来（）．（A）一定带正电（B）可能带正电（C）一定带负电出）可能带负电错解（C）．分析验电器是利用电荷间存在的相互作用力的原理制成的．当验电器带上一定量的 The subject had a positive charge on the metal ball A equipped with an insulated handle to contact the metal ball B of the electroscope and found that the angle of the metal foil of the electroscope was smaller. This shows the original electroscope (). (A) must be positively charged (B) may be positively charged (C) must be negatively charged) may be negatively charged (C). The analysis of electroscope is based on the principle of the interaction force existing between the charges. When the electroscope carries a certain amount of